Generating arterial endothelial cell populations

ABSTRACT

Methods for generating human arterial endothelial cells under defined conditions in the absence of insulin are described.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No. 62/118,553, filed Feb. 20, 2015, which is incorporated herein by reference in its entirety.

STATEMENT REGARDING FEDERALLY FUNDED RESEARCH OR DEVELOPMENT

This invention was made with government support under UH2-TR000506 awarded by the National Institutes of Health (National Center for Advancing Translational Sciences). The government has certain rights in the invention.

BACKGROUND

Cardiovascular disease is the leading cause of death in U.S., and most vascular diseases, such as atherosclerosis, occur in the arteries. Atherosclerosis is a chronic inflammatory disease that is initiated by activation, dysfunction, and structural changes of the endothelial cells, leading to increased leukocyte-endothelial adhesion.

Generating arterial endothelial cells from pluripotent stem cells holds great promise for the development of therapies for diseases or conditions that would treat cardiovascular disease. However, arterial endothelial development is challenging, as primary arterial endothelial cells undergo de-differentiation in culture. For instance, U.S. Published Patent Application No. 2009/0104159 to Prosper et al. describes methods of culturing and using vascular endothelial cells that demonstrate the “potential” for arterial differentiation (paragraph [0136]). Further, U.S. Published Patent Application No. 2012/0064040 to McCloskey et al. describes chemically defined culture conditions to derive endothelial cells from embryonic stem cells. However, here again, this disclosure appears to merely demonstrate the potential for differentiating arterial endothelial cells from embryonic stem cells, and achieves very low results.

Existing protocols for deriving arterial endothelial cells from human embryonic stem cells have been largely unsuccessful. Accordingly, there remains a need in the art for efficient, defined, and scalable methods for generating human arterial endothelial cells from human pluripotent stem cells.

SUMMARY OF THE INVENTION

In a first aspect, provided herein is a method of obtaining arterial endothelial cells. The method can comprise or consist essentially of culturing mesodermal cells in a serum-free, albumin-free, chemically defined culture medium that is substantially free of insulin and comprises a fibroblast growth factor (FGF), a vascular endothelial growth factor (VEGF), and at least one of a Notch agonist, a TGF-beta inhibitor, and an inhibitor of inositol monophosphatase, whereby a cell population comprising arterial endothelial cells is obtained. The arterial endothelial cells of the population can express one or more markers selected from the group consisting of neuropilin1 (NRP-1), Delta-like 4 (DLL4), ephrin-B2 (EFNB2), CD44, CXCR4/CD184, Gap Junction Protein Alpha-4 (GJA4), Hey1, Jagged-1 (JAG1), Notch1, and Notch4. The cell population can comprise at least 80% arterial endothelial cells.

The serum-free, albumin-free, chemically defined culture medium can comprise a FGF, a VEGF, a Notch agonist, a TGF-beta inhibitor, and an inhibitor of inositol monophosphatase. The mesodermal cells can express one or more mesodermal markers selected from the group consisting of Brachyury (T), EMOS, FOXA2, MIXL1, MSX1, and MSX2.

In some cases, the mesodermal cells are obtained by culturing human pluripotent stem cells for a period of about two days in a serum-free, albumin-free, chemically defined cell culture medium comprising a Bone Morphogenetic Protein (BMP), Activin A, and an activator of Wnt/β-catenin signaling to obtain a cell population comprising mesodermal cells. The mesodermal cells can express one or more mesodermal markers selected from the group consisting of Brachyury (T), EMOS, FOXA2, MIXL1, MSX1, and MSX2. The pluripotent stem cells can be human embryonic stem cells or human induced pluripotent stem cells. The activator of Wnt/β-catenin signaling can be a Gsk3 inhibitor. The Gsk3 inhibitor can be selected from the group consisting of CHIR 99021, CHIR 98014, BIO-acetoxime, BIO, LiCl, SB 216763, SB 415286, AR A014418, 1-Azakenpaullone, and Bis-7-indolylmaleimide. The Notch agonist can be selected from the group consisting of Resveratrol (3,4′,5-trihydroxystilbene), valproic acid, and suberoyl bishydroxamic acid. The TGF-beta inhibitor can be SB431542. The inhibitor of inositol monophosphatase can be L-690,330.

In another aspect, provided herein is a substantially pure, isolated population of arterial endothelial cells obtained according to a method provided herein. The isolated population can comprise at least 90% arterial endothelial cells or at least 99% arterial endothelial cells.

In another aspect, provided herein is a substantially pure, isolated population of pluripotent stem cell-derived arterial endothelial cells obtained according to a method provided herein. The isolated population can comprise at least 90% arterial endothelial cells or at least 99% arterial endothelial cells.

In a further aspect, provided herein is a method of in vitro screening test agents. The method can comprise contacting a test agent to arterial endothelial cells obtained according to a method provided herein; and detecting an effect of the agent on the contacted arterial endothelial cells. Detecting can comprise performing a method selected from the group consisting of leukocyte adhesion assay, RNA sequencing, gene expression profiling, transcriptome analysis, metabolome analysis, detecting reporter or sensor, protein expression profiling, Forster resonance energy transfer (FRET), metabolic profiling, and microdialysis.

In yet another aspect, provided herein is a kit for obtaining arterial endothelial cells, the kit comprising: (i) a serum-free, albumin-free, chemically defined culture medium suitable for differentiation of mesodermal cells into arterial endothelial cells, wherein the culture medium is substantially free of insulin and comprises a fibroblast growth factor (FGF), a vascular endothelial growth factor (VEGF), and at least one of a Notch agonist, a TGF-beta inhibitor, and an inhibitor of inositol monophosphatase; and (ii) instructions describing a method for differentiating mesodermal cells into arterial endothelial cells, the method employing the culture medium. The kit can further comprise (a) a serum-free, albumin-free, chemically defined culture medium suitable for differentiation of human pluripotent stem cells into mesodermal cells, where the culture medium comprises a BMP, Activin A, and an activator of Wnt/β-catenin signaling; and (b) instructions describing a method for differentiating human pluripotent stem cells into arterial endothelial cells, the method employing the culture medium of (a).

These and other features, aspects, and advantages of the present invention will become better understood from the description that follows. In the description, reference is made to the accompanying drawings, which form a part hereof and in which there is shown by way of illustration, not limitation, embodiments of the invention. The description of preferred embodiments is not intended to limit the invention to cover all modifications, equivalents and alternatives. Reference should therefore be made to the claims recited herein for interpreting the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.

The following drawings form part of the present specification and are included to further demonstrate certain aspects of the compositions and methods provided herein. The invention may be better understood by reference to one or more of these drawings in combination with the detailed description of specific embodiments presented herein.

FIGS. 1A-1D demonstrate single-cell RNA-seq. (A) Hierarchical clustering analysis of arterial and venous genes of single cells. (B) Average arterial and venous gene expression of five cell subpopulations. In each subpopulation, the average TPM (transcript per million) of each gene was calculated and normalized to population P1 (arterial genes) or P3 (venous genes). The normalized expression of all arterial genes or venous genes was further averaged and shown in a bar graph. Data were represented as mean±SD. *: P<0.05, n=13 cells in P1, n=10 cells in P3. (C) Principal component analysis of P1 and P3. The plot was generated by Singular™ Analysis Toolset 2.1. (D) Arterial enriched genes. The mean TPM of each gene for P1 was compared to P3 to calculate fold change. P-value was also calculated by comparing P1 to P3. Arterial enriched genes were identified with fold change>2, P value<0.1, and the mean TPM of P1>10. P<0.1 was used as the cut off since the P value of the previously reported arterial genes, VEGFa, Fzd4, Fzd7, Fzd10, Dll4, and Notch4, was between 0.01 to 0.1.

FIG. 2A provides a schematic representation of a protocol for generating arterial endothelial cells from human pluripotent stem cells using a chemically-defined medium listed in Table 1. Human embryonic stem (ES) cells were first differentiated into mesoderm cells using E8BAC medium. E6 medium supplemented with growth factors or small molecules (E6FVB) was then used to induce mesoderm cells to differentiate into endothelial cells. FIG. 2B is flow cytometric data for of CD31 and CD34 expression at day 0 (undifferentiated pluripotent state) and at day 5 (differentiated state). FIG. 2C is flow cytometric data for KDR, NANOG, and OCT4 expression at day 0 and at day 5. FIG. 2D indicates CD144 expression on purified endothelial cells by immunostaining. FIG. 2E shows a LDL (low density lipoprotein) uptake assay. FIG. 2F shows an in vitro MATRIGEL® (BD Biosciences, Falcon®) encapsulation assay. FIG. 2G shows the results of an in vivo MATRIGEL® gel plug assay for analysis of migration and angiogenesis. Anti-human CD31-specific antibody was used for immunostaining to detect vascular formation in recovered gel plugs. FIG. 2H shows flow cytometric analysis of CD31 and CD34 expression after five days of differentiation in the indicated combinations of growth factors and small molecules. Insulin was included in each combination. When the differentiation medium included a TGF inhibitor, SB431542 was included at 10 μM.

FIGS. 3A-3F present candidate pathways critical for arteriovenous specification. (A) Flow cytometric analysis of EFNB2-tdTomato and EPHB4-EGFP expression on CD31 and CD144 gated endothelial cells. EFNB2-tdTomato/EPHB4-EGFP dual reporter cells (hetero knock-in in H1 cells for each gene) were first differentiated into mesoderm cells by E8BAC medium (E8 medium supplemented with BMP4, Activin-A, and CHIR99021). E5 (E8 medium minus FGF2, TGFβ1, and insulin) medium supplemented with 100 ng/ml FGF2, 50 ng/ml VEGFA, and 50 ng/ml BMP4 was used to induce mesoderm cells to differentiate into endothelial cells from day 2 to day 6. Either Insulin (20 μg/ml) or Ly294002 (1611M, a PI3K inhibitor) was added to the medium as indicated from day 2 to day 6. (B) Statistics of EFNB2-tdTommato^(high)/EPHB4-EGFP^(low) cells. Data are represented as mean±SD. *: P<0.05, n=5. (C) Western blots showing AKT activity. Protein was harvested at day 3. (D) Flow cytometric analysis of EFNB2-tdTomato and EPHB4-EGFP expression on CD31 and CD144 gated endothelial cells. E5 medium supplemented with 50 ng/ml VEGFA, 50 ng/ml BMP4 or 1011M SB431542 was used to induce mesoderm cells to differentiate into endothelial cells from day 2 to day 6. (E) Flow cytometric analysis of EFNB2-tdTomato and EPHB4-EGFP expression on CD31 and CD144 gated endothelial cells. ES cells were first differentiated into mesoderm cells as mentioned above. E5 medium supplemented with 50 ng/ml VEGFA and 1011M SB431542 was used as the base medium induce mesoderm cells to differentiate into endothelial cells from day 2 to day 6. Other factors were added to the base medium as indicated. (F) Statistics of EFNB2-tdTomato^(high)/EPHB4-EGFP^(low) cells. 5 μM L690, 5 μg/ml LDL, and 100 ng/ml PDGF-BB were used. *: P<0.05, n=3.

FIGS. 4A-4H present flow cytometric analysis of expression of EphrinB2 and Ephrin Type B Receptor 4 reporter constructs (EFNB2-tdTomato and EPHB4-EGFP) on CD31- and CD144-gated endothelial cells obtained after differentiation in various medium, as described. FIG. 4B illustrates the percentage of arterial endothelial cells (AEC) (EFNB2-tdTomato^(high)/EPHB4-EGFP^(low)) obtained after differentiation in the various medium conditions of FIG. 4A. Data are represented as mean±SD. FIG. 4C shows flow cytometric analysis of expression of CXCR4 and CD144 on endothelial cells obtained after differentiation in various medium. FIG. 4D illustrates the percentage of CXCR4⁺CD144⁺ arterial endothelial cells obtained after differentiation in the various medium conditions of FIG. 4C. FIG. 4E shows flow cytometric analysis of expression of DLL4 and CD144 on endothelial cells obtained after differentiation in various medium. FIG. 4F illustrates the percentage of DLL4⁺CD144⁺ arterial endothelial cells obtained after differentiation in the various medium conditions of FIG. 4E. 5 μM L-690,330 (a bisphosphonate inhibitor of inositol monophosphatase), and 100 ng/ml PDGF-BB (platelet derived growth factor BB) were used. FIG. 4G shows the statistics of arterial endothelial cell number generated from 1.0×10⁶ starting ES cells after six days of differentiation (“five factors” medium). FIG. 4H shows the expansion of EFNB2-tdTomato^(high)/EPHB4-EGFP^(low) cells from passage 0 to passage 4.

FIGS. 5A-5G present characterization of arterial endothelial cells. All arterial endothelial cells were derived by “five factors” medium. (A) TPM of bulk RNA-seq was shown. EFNB2-tdTomato^(high)/EPHB4-EGFP^(low) (AECs) were sorted for RNA-seq. The ratio of AECs (average TPM from AEC1 and AEC2) to HUVEC was calculated. AoEC, cultured aortic endothelial cells. (B) PCA of single-cell RNA-seq. AECs: sorted EFNB2-tdTomato^(high)/EPHB4-EGFP^(low) cells, pAECs: primary arterial endothelial cells from freshly isolated human fetus dorsal aorta, ES: H1 ES cells. (C) LDL uptake. Scale bar=100 Arterial endothelial cells (passage 2) derived from wild type H1 cells were used. The purity was about 93% after being passaged, so cells used in panels C-H were not purified. (D) Matrigel encapsulation assay. Arterial endothelial cells (passage 3) derived from reporter cell line were used. Scale bar=100 (E) Vascular formation in fibrin gel. Arterial endothelial cells (passage 2) derived from wild type H1 cells were used for panels E-F. Scale bar=100 (F) Lumen formation of endothelial cells and pericytes co-cultured in fibrin gel. To visualize the lumen, cells were stained with CMFDA (green). Y-z and x-z projection was shown. Scale bar=100 (G) Endothelial cells formed functional vessels in vivo. Wild type H1 derived-arterial endothelial cells (passage 2, purified by CD144 microbeads) were mixed with Matrigel™ and injected into SCID mice. After four weeks, rhodamine-dextran was retro-orbital injected to highlight perfused vessels. Scale bar=100 μm. CD31: anti human and mouse CD31 antibody, Santa Cruz, cat #SC-1506. hCD144: anti-human CD144-647 antibody, BD biosciences, cat #561567.

FIGS. 6A-6F demonstrate that arterial endothelial cells improve vascular function. (A) Flat-mounted retinas of oxygen-induced retinopathy. Endothelial cells were stained by CD31 antibody. Vaso-obliteration area was outlined. Scale bar=0.5 mm. (B) Statistics of vaso-obliteration. **: P<0.01. The P value was calculated by comparing to vehicle group. Vehicle group: n=12, from three independent experiments, PBS was used. AECs group: n=16, from two independent experiments. HUVEC group: n=5. Fibroblast group: n=5. (C) Neovascular tuft was indicated by the arrow. Endothelial cells were stained by CD31 antibody. Scale bar=0.5 mm. (D) Representative laser Doppler perfusion imaging showing the blood flow in ischemia athymic mice. (E) A stacked bar graph showing the physiological status at post-operative day 40. Vehicle group: n=10, DF12 medium was used. 0.3M AECs group: n=11, 3×10⁵ AECs were injected per mouse. 1M AECs group: n=10, 1×10⁶ AECs were injected per mouse. 1M cord blood-derived endothelial colony forming cells (CB-ECFCs) group: n=10, 1×10⁶ CB-ECFCs were injected per mouse. The animal death was caused by ischemia related infection. **, P<0.001 (Chi-squared test, compared to vehicle group). (F) AECs formed vessels and recruited smooth muscle cells in mouse limb. AECs were stained with human specific CD31 antibody. Scale bar=100 μm. hCD31: anti human CD31 antibody, BD biosciences, cat #550274.

FIGS. 7A-7F present arterial-specific functional characterization of endothelial cells. (A) Nitric oxide (NO) production was revealed by the intensity of 4-amino-5-methylamino-2′,7′-difluororescein diacetate (DAF-FM), which is a NO-sensitive reagent that is useful for qualitative assessment of cellular NO production. Arterial endothelial cells (AECs) were derived from wild type H1 cells by “five factors” medium and used for experiments at passage 2 or 4. DAF-FM is nonfluorescent until it reacts with NO to form a fluorescent benzotriazole. The fluorescent intensity was measured by flow cytometry. Experiment was performed three times and typical data from one assay was shown. (B) Oxygen consumption rate was measured on XF24 analyzers (Seahorse Bioscience). Oligomycin was used to abolish the oxygen consumption. Carbonyl cyanide-4-(trifluoromethoxy)phenylhydrazone (FCCP), which is a potent uncoupler of oxidative phosphorylation in mitochondria that disrupts ATP synthesis by transporting protons across cell membranes, was used to measure maximal respiration capacity. Antimycin A and Rotenone were applied simultaneously to completely block the electron transport chain. *: P<0.05, n=3. The P value was calculated by comparing to HUVEC. HCAEC, human coronary arterial endothelial cells. (C) Shear Stress response performed on ibidi Pump System (Red perfusion set, μ-Slide VI 0.4. (D) The statistics data of shear stress response. Ratio of cell length to width was used to demonstrate the elongation of cells in response to shear stress. For each cell type, 100 cells were measured to do the statistics. Data are represented as mean±SD. *: P<0.05; ***:P<0.001, n=100 cells from three independent experiments. (E) Leukocyte (round cells) adhesion assay. Scale bar=200 μm. AECs were used at passage 1 or 4. (F) Statistics of leukocyte adhesion assay. Leukocyte number was counted for each image. Data are represented as mean±SD. *: P<0.05, n=3 images from three independent experiments. The P value was calculated by comparing to HUVEC with TNFα treatment.

FIGS. 8A-8J present data for the generation and characterization of the reporter cell line. (A) Schematic of wild type and targeted EFNB2-tdTomato allele. H1 ES cells were used for gene targeting. Tom: tdTomato. (B) Schematic of wild type and targeted EPHB4-EGFP allele. (C) Junction PCR of 5′ arm and 3′ arm of EFNB2-tdTomato alleles. WT: wild type, C14: clone 14 of targeted cells. (D) Southern blot of EFNB2 wild type and knock-in (EFNB2-tdTomato) alleles. (E) Junction PCR of 5′ arm and 3′ arm of EPHB4-EGFP allele. C29: clone 29 of targeted cells. (F) Southern blot of EPHB4-EGFP allele. (G) qPCR analysis of tdTomato copy number of EFNB2-tdTomato cell line (clone 14). Data are represented as mean±SD. n=3. Con: control samples with one copy of tdTomato. (H) qPCR analysis of EGFP copy number of EFNB2-tdTomato/EPHB4-EGFP cell line (clone 29). Data are represented as mean±SD. n=3. Con: control samples with one copy of EGFP. (I) Comparing of endogenous EFNB2 and EPHB4 gene expression of wild type and reporter cell lines by RT-qPCR. Day 5, differentiation for five days. Data are represented as mean±SD. n=3. (J) Karyotyping of EFNB2-tdTomato/EPHB4-EGFP cell line (clone 29).

FIG. 9 presents flow cytometric analysis of EFNB2-tdTomato and EPHB4-EGFP expression. Purified AECs were cultured in E5 medium supplemented with growth factors or small molecules for three days. F: 100 ng/ml, V: 50 ng/ml VEGFA, I: 10 μM SB431542, W: 100 ng/ml WNT3A, L: 10 μM L-690,330, R: 5 μM RESV. Ins: 10 μg/ml insulin. Lower EPHB4-EGFP and higher EFNB2-tdTomato expression were observed in cultures with FVIR, FVIR+Ins, and FVIRLW medium.

FIG. 10 presents a heat-map of expression obtained using single-cell RNA-seq. Hierarchical clustering analysis was performed for arterial and venous genes of EFNB2-tdTomato^(high)/EPHB4-EGFP^(low) AECs derived by the “five factors” protocol as described herein.

FIGS. 11A-11C present arterial endothelial cell differentiation data. (A) Schematic of arterial endothelial cell differentiation protocol. ES cells were first differentiated into mesoderm cells by E8BAC medium (E8 medium supplemented with 5 ng/ml BMP4, 25 ng/ml Activin A, and 1 μM CHIR99021). E5 (E8 medium minus FGF2, TGFβ1, and insulin) medium supplemented with 100 ng/ml FGF2 and 10 μM SB431542 was then used to induce mesoderm cells to differentiate into endothelial cells. (B) Flow cytometric analysis of CD31 and CD34 expression. E5+100 ng/ml FGF2+10 μM SB431542 medium (“Control”) supplemented with 50 ng/ml VEGF, 5 μM RESV (resveratrol, a Notch activator), or 50 ng/ml WNT3A was used to induce mesoderm cells to differentiate into arterial endothelial cells. (C) Flow cytometric analysis of EFNB2-tdTomato and EPHB4-EGFP expression.

FIG. 12 demonstrates MYH11-positive vascular smooth muscle in mouse heart, limb, and intestine. In mouse heart and limb, MYH11-positive vascular smooth muscle is recruited to the blood vessels. In the intestine, smooth muscle cells express both MYH11 and CD31 (arrow indicated), demonstrating that MYH11⁺CD31⁻ cells are vascular smooth muscle cells while MYH11⁺CD31⁺ cells are intestinal smooth muscle cells.

DETAILED DESCRIPTION OF THE INVENTION

All publications, including but not limited to patents and patent applications, cited in this specification are herein incorporated by reference as though set forth in their entirety in the present application.

The present invention is based, at least in part, on the Inventors' discovery that arterial endothelial cell differentiation was greatly improved by combining several specific factors as compared to single factors. As described herein, the inventors further discovered that certain factors (insulin, TGFβ, and PDGF) inhibit arterial endothelial differentiation.

Methods

In exemplary embodiments, the methods provided herein comprise differentiating mesodermal stem cells into arterial endothelial cells. As used herein, the term “arterial endothelial cell” (AEC) refers to cells of the arterial vascular endothelial lineage obtained according to a method provided herein. AECs of the present invention are characterized by high levels of expression of arterial endothelium markers such as EphrinB2, DLL4, Hey-2, jagged-1, and jagged-2. AECs are also characterized by low leukocyte adhesion, higher NO production and oxygen consumption, response to shear stress, and capacity to form vascular networks in vitro and in vivo while maintaining expression of arterial markers in such networks. AECs are distinguishable from other cell types, including endothelial cells (ECs), venous endothelial cells, and endothelial progenitor cells, on the basis of characteristic expression profiles and functional attributes of the cells in vitro as described herein.

In a first aspect, provided herein is a method of obtaining arterial endothelial cells. In exemplary embodiments, the method comprises directing differentiation of mesodermal cells into cells of the arterial endothelial cell lineage. As used herein, the terms “mesodermal cell” and “mesoderm cell” are used interchangeably and refer to a cell having mesoderm-specific gene expression and being capable of differentiating into a mesodermal lineage such as bone, muscle such as cardiac muscle, skeletal muscle and smooth muscle (e.g., of the gut), connective tissue such as the dermis and cartilage, kidneys, the urogenital system, blood or hematopoietic cells, heart and vasculature. Mesoderm-specific biomarkers include Brachyury (T).

Throughout the AEC differentiation steps provided herein, mesodermal cells are typically cultured in a culture medium that is free, substantially free, or essentially free of insulin, albumin, or any component derived from a non-human animal (i.e., free of xenogeneic material). As used herein, the term “substantially free” refers to cell culture conditions substantially devoid of a certain component or reagent. Substantially free of insulin means the medium contains less than 1% of original concentration of insulin, or less than 2×10⁻⁵% of insulin by weight, and preferably contains less than 1×10⁻⁵%, less than 0.5×10⁻⁵%, less that 0.2×10⁻⁵% or less that 0.1×10⁻⁵% of insulin.

In addition, the culture medium comprises, or consists essentially of, one or more of a Fibroblast Growth Factor (FGF), a vascular endothelial growth factor (VEGF), an inhibitor of TGF-beta signaling (e.g., SB431542), Resveratrol (RESV), and an inhibitor of inositol monophosphatase, where culturing occurs for a length of time sufficient for the cultured mesoderm cells to differentiate into arterial endothelial cells. In some embodiments, the cell culture medium used for AEC differentiation methods described herein comprises each of these components. In other cases, the culture medium is substantially free of one or more of these ingredients. Culturing can take place on any appropriate surface (e.g., in two-dimensional or three-dimensional culture).

In some cases, a mesodermal cell (including, in some cases, a pluripotent stem-cell derived mesodermal cell) is cultured in medium that comprises an FGF, VEGF, a Notch agonist, a TGFβ receptor inhibitor, and an inhibitor of inositol monophosphatase in amounts effective to direct differentiation of a mesodermal cell to the arterial endothelial lineage. In some cases, the FGF is FGF2. VEGF is a heparin-binding glycoprotein that acts as a specific endothelial cell mitogen. In some cases, the VEGF is VEGF-A (vascular endothelial growth factor A) or an isoform thereof (e.g., VEGF-165). Exemplary human VEGF-A protein sequences comprise Genbank: AAH65522.2 and GenBank: AAH1 1177.2, and the nucleic acids encoding all of or encoding the non-precursor part of such are encompassed.

TGFβ receptor inhibitors appropriate for use in a method of the present invention include, without limitation, SB-431542, SB-525334, A83-01, LY2157299, LY210976, GW788388, RepSox, SB-505124, D4476, GW788388, SD208, and EW-7197. Preferably, the inhibitor of TGF-beta signaling is SB431542, a small molecule inhibitor of endogenous activin and the type I receptor (TGFβ Receptor I) (Inman et al., Mot Pharmacol. 62(1):65-74 (2002).

Notch is a single-pass cell-surface receptor that binds to a family of cell-surface ligands including the Delta-like and Jagged families. As used herein, the terms “Notch agonist” and “Notch activator” refer to molecules (e.g., biomolecules, small molecules, chemicals) that bind to Notch receptor and initiate or mediumte signaling events associated with Notch activation. Resveratrol (3,4′,5-trihydroxystilbene) belongs to a class of polyphenolic compounds called stilbenes and is an activator (agonist) of Notch signaling. Other Notch agonists appropriate for use according to methods for promoting arterial differentiation provided herein include valproic acid and suberoyl bishydroxamic acid. In addition, immobilized or multimerized soluble Notch ligands such as immobilized DLL4 and immobilized Jagged-1 peptide also can be used as Notch activators.

Inositol monophosphatase (IMPase) catalyses the hydrolysis of myo-inositol monophosphates to myo-inositol, which is required in the phosphoinositide cell signaling pathway. In some cases, an inhibitor of IMPase is the biphosphonate L-690,330 ([1-(4-Hydroxyphenoxy)ethylidene]bisphosphonic acid). Lithium also inhibits IMPase to attenuate phosphoinositide signaling (Berridge et al., Cell 59:411-419 (1989)). Other inhibitors of the phosphoinositide signaling pathway include, without limitation, phosphoinositide 3-kinase (PI3K) inhibitor Ly294002, Pictilisib, HS-173, GSK2636771, Duvelisib, TG100-115, GSK1059615, PF-04691502, PIK-93, BGT226, AZD6482, SAR245409, BYL719, CUDC-907, IC-87114, TG100713, Gedatolisib, CH5132799, PKI-402, BAY 80-6946, XL147, PIK-90, PIK-293, PIK-294, Quercetin, Wortmannin, ZSTK474, AS-252424, AS-604850, and Apitolisib.

A suitable working concentration range for chemical inhibitors such as those described herein is from about 0.1 μM to about 100 μM, e.g., about 2 μM, 5 μM, 7 μM, 10 μM, 12 μM, 15 μM, 18 μM, or another working concentration of one or more the foregoing chemical inhibitors between about 0.1 μM to about 100 μM.

Preferably, mesodermal cells are cultured in the AEC differentiation medium until at least about 80% (e.g., at least 80%, 85%, 90%, 95%, 99%) of the resulting cell population are arterial endothelial cells. Arterial endothelial cells characteristically have the following expression profile: CD31⁺/CD144⁺/CD41⁻/CD45⁻.

For several of the biological markers described herein, expression will be low or intermediate in level. While it is commonplace to refer to cells as “positive” or “negative” for a particular marker, actual expression levels are a quantitative trait. The number of molecules on the cell surface can vary by several logs, yet still be characterized as “positive.” Accordingly, characterization of the level of staining permits subtle distinctions between cell populations. Expression levels can be detected or monitored by flow cytometry, where lasers detect the quantitative levels of fluorochrome (which is proportional to the amount of cell surface antigen bound by the antibodies). Flow cytometry or fluorescence-activated cell sorting (FACS) can be used to separate cell populations based on the intensity of antibody staining, as well as other parameters such as cell size and light scatter. Although the absolute level of staining may differ with a particular fluorochrome and antibody preparation, the data can be normalized to a control.

Any appropriate method can be used to detect expression of biological markers characteristic of cell types described herein. For example, the presence or absence of one or more biological markers can be detected using, for example, RNA sequencing (e.g., RNA-seq), immunohistochemistry, polymerase chain reaction, quantitative real time PCR (qRT-PCR), or other technique that detects or measures gene expression. RNA-seq is a high-throughput sequencing technology that provides a genome-wide assessment of the RNA content of an organism, tissue, or cell. Alternatively, or additionally, one may detect the presence or absence or measure the level of one or more biological markers of AECs using, for example, via fluorescent in situ hybridization; (FISH; see WO98/45479 published October, 1998), Southern blotting, Northern blotting, or polymerase chain reaction (PCR) techniques, such as qRT-PCR. In exemplary embodiments, a cell population obtained according to a method provided herein is evaluated for expression (or the absence thereof) of biological markers of arterial endothelial cells such as EFNB2, Cxcr4, Delta-like 4 (DLL4), Gja4, Hey1, Jag1, Notch1, Notch4, and Nrp1. Preferably, AECs express one or more of the following arterial endothelial cell markers: Ephrin B2 (EFNB2), Neuropilin-1 (NRP-1)/CD304, Delta-like 4 (DLL4), and CD184 (cluster of differentiation 184). The Ephrin B2 (EFNB2) gene encodes an EFNB class ephrin that binds to the EPHB4 and EPHA3 receptors. Neuropilin-1 (NRP1), which is also known as vascular endothelial cell growth factor 165 receptor (VEGF165R), is primarily expressed in arterial endothelial cells. DLL4 is a Notch ligand expressed in arterial endothelial cells (Shutter et al., Genes & Dev. 14:1313-18 (2000)). CD184 is also known as CXCR4 (C—X—C chemokine receptor type 4) or fusin. Quantitative methods for evaluating expression of markers at the protein level in cell populations are also known in the art. For example, flow cytometry is used to determine the fraction of cells in a given cell population that express or do not express biological markers of interest.

The terms “defined culture medium,” “defined medium,” and the like, as used herein, indicate that the identity and quantity of each medium ingredient is known. As used herein, the terms “chemically-defined culture conditions,” “fully defined, growth factor free culture conditions,” and “fully-defined conditions” indicate that the identity and quantity of each medium ingredient is known and the identity and quantity of supportive surface is known. As used herein, the term “albumin-free conditions” indicates that the culture medium used contains no added albumin in any form, including without limitation Bovine Serum Albumin (BSA), any form of recombinant albumin, or any other animal components.

Human pluripotent stem cells (hPSCs), either embryonic or induced, provide access to the earliest stages of human development and offer a platform on which to derive a large number of vasculogenic cells for cellular therapy and tissue engineering. Accordingly, in exemplary embodiments, the methods provided herein further comprise differentiating human pluripotent stem cells under conditions that promote differentiation of mesodermal stem cells into arterial endothelial cells. In such, a method of producing an arterial endothelial cell comprises culturing human pluripotent stem cells in a serum-free, albumin-free, chemically defined culture medium that promotes mesoderm differentiation. In this manner, pluripotent stem cell-derived mesodermal cells are differentiated according to the AEC differentiation methods provided herein, thus producing pluripotent stem cell-derived AECs. In exemplary embodiments, the serum-free, albumin-free, chemically defined culture medium that promotes mesoderm differentiation comprises Activin A, Bone Morphogenetic Protein 4 (BMP4), FGF2, and an activator of Wnt/β-catenin signaling.

Defined medium and substrate conditions for culturing pluripotent stem cells, as used in the methods described herein, are well known in the art. The medium used herein are limited only in that they are albumin-free. In some cases, pluripotent stem cells to be differentiated according to the methods disclosed herein are cultured in a serum-free, albumin-free medium.

As will be appreciated by those of ordinary skill in the art, Wnt/β-catenin signaling can be activated by modulating the function of one or more proteins that participate in the Wnt/β-catenin signaling pathway to increase β-catenin expression levels or activity, TCF and LEF expression levels, or β-catenin/TCF/LEF induced transcriptional activity.

In some embodiments, activation of Wnt/3-catenin signaling is achieved by inhibition of Gsk3 phosphotransferase activity or Gsk3 binding interactions. While not wishing to be bound by theory, it is believed that inhibition of Gsk3 phosphorylation of β-catenin will inhibit tonic degradation of β-catenin and thereby increase β-catenin's level and activity to drive differentiation of pluripotent stem cells to an endodermal/mesodermal lineage. Gsk3 inhibition can be achieved in a variety of ways including, but not limited to, providing small molecules that inhibit Gsk3 phosphotransferase activity, RNA interference knockdown of Gsk3, and overexpression of dominant negative form of Gsk3. Dominant negative forms of Gsk3 are known in the art as described, e.g., in Hagen, T. et al. J Biol Chem, 277:23330-5 (2002), which describes a Gsk3 comprising a R96A mutation.

In some embodiments, the Wnt/β-catenin signaling pathway is activated by inhibiting Gsk3 in pluripotent stem cells by contacting the pluripotent stem cells with a small molecule that inhibits Gsk3 phosophotransferase activity or Gsk3 binding interactions. Suitable small molecule Gsk3 inhibitors include, but are not limited to, CHIR 99021, CHIR 98014, BIO-acetoxime, BIO, LiCl, SB 216763, SB 415286, AR A014418, 1-Azakenpaullone, Bis-7-indolylmaleimide, and any combinations thereof. In some embodiments, any of CHIR 99021, CHIR 98014, and BIO-acetoxime are used to inhibit Gsk3 in pluripotent stem cells in the differentiation methods described herein. In one embodiment, the small molecule Gsk3 inhibitor to be used is CHIR99021 at a concentration ranging from about 1 μM to about 9 μM, e.g., about 1 μM, 2 μM, 3 μM, 4 μM, 5 μM, 6 μM, 7 μM, 8 μM, 9 μM or another concentration of CHIR99021 from about 1 μM to about 9 μM. In another embodiment, the small molecule Gsk3 inhibitor to be used is CHIR 98014 at a concentration ranging from about 0.1 μM to about 1 μM, e.g., about 0.1 μM, 0.2 μM, 0.3 μM, 0.4 μM, 0.5 μM, 0.6 μM, 0.7 μM, 0.8 μM, 0.9 μM, 1.0 μM or another concentration of CHIR-98014 from about 0.1 μM to about 1 μM. In another embodiment, the small molecule Gsk3 inhibitor to be used is BIO-acetoxime at a concentration ranging from about 0.1 μM to about 1 μM, e.g., about 0.1 μM, 0.2 μM, 0.3 μM, 0.4 μM, 0.5 μM, 0.6 μM, 0.7 μM, 0.8 μM, 0.9 μM, 1.0 μM or another concentration of BIO-acetoxime from about 0.1 μM to about 1 μM.

In other embodiments, Gsk3 activity is inhibited by RNA interference knockdown of Gsk3. For example, Gsk3 expression levels can be knocked-down using commercially available siRNAs against Gsk3, e.g., SignalSilence® GSK-3α/β siRNA (catalog #6301 from Cell Signaling Techology®, Danvers, MA), or a retroviral vector with an inducible expression cassette for Gsk3, e.g., a commercially available Tet-inducible retroviral RNAi system from Clontech (Mountainview, CA) Catalog No. 630926, or a cumate-inducible system from Systems Biosciences, Inc. (Mountainview, CA), e.g., the SparQ® system, catalog no. QM200PA-2. In other embodiments, the Wnt/β-catenin signaling pathway is activated by overexpressing β-catenin itself, e.g., human β-catenin (GenBank Accession Nos: X87838 and CAA61107.1 for nucleotide and protein sequences, respectively). In one embodiment, β-catenin overexpression is inducible β-catenin overexpression achieved using, e.g., any of the just-mentioned inducible expression systems. Alternatively, a constitutively active, stabilized isoform of β-catenin is used, which contains point mutations S33A, S37A, T41A, and S45A as described, e.g., in Baba, Y. et al. Constitutively active β-catenin confers multi-lineage differentiation potential on lymphoid and myeloid progenitors. Immunity 23:599-609 (2005).

In yet other embodiments, Wnt/β-catenin signaling pathway activation in pluripotent stem cells is achieved by contacting the cells with an agent that disrupts the interaction of β-catenin with Axin, a member of the β-catenin destruction complex. Disruption of the Axin-β-catenin interaction allows β-catenin to escape degradation though the destruction complex thereby increasing the net level of β-catenin to drive β-catenin signaling. For example, the Axin-β-catenin interaction can be disrupted in pluripotent cells by contacting them with the compound (“SKL2001”), which is commercially available, e.g., as catalog no. 681667 from EMD4 Biosciences. An effective concentration of SKL2001 to activate Wnt/β-catenin signaling ranges from about 10 μM to about 100 μM, about 20 μM, 30 μM, 40 μM, 50 μM, 60 μM, 70 μM, 80 μM, 90 μM or another concentration of SKL2001 from about 10 μM to about 100 μM. In some embodiments the activator of Wnt/β-catenin signaling is a Gsk3 inhibitor. In some embodiments the Gsk3 inhibitor is selected from the group consisting of CHIR99021, CHIR98014, BIO-acetoxime, BIO, LiCl, SB216763, SB415286, AR A014418, 1-Azakenpaullone, and Bis-7-indolylmaleimide. In some embodiments the Gsk3 inhibitor is CHIR99021 or CHIR98014 at a concentration between about 0.1 μM to about 10 μM in the medium. In one embodiment, the small molecule Gsk3 inhibitor to be used is CHIR99021 at a concentration ranging from about 1 μM to about 9 μM, e.g., about 1 μM, 2 μM, 3 μM, 4 μM, 5 μM, 6 μM, 7 μM, 8 μM, 9 μM or another concentration of CHIR99021 from about 1 μM to about 9 μM. In another embodiment, the small molecule Gsk3 inhibitor to be used is CHIR98014 at a concentration ranging from about 0.1 μM to about 1 μM, e.g., about 0.1 μM, 0.2 μM, 0.3 μM, 0.4 μM, 0.5 μM, 0.6 μM, 0.7 μM, 0.8 μM, 0.9 μM, 1.0 μM or another concentration of CHIR98014 from about 0.1 μM to about 1 μM.

In exemplary embodiments, pluripotent stem cells are cultured in a chemically defined culture medium comprising or consisting essentially of DMEM/F12 culture medium, L-ascorbic acid-2-phosphate magnesium, sodium selenium, human FGF2, insulin, NaHCO₃, transferrin, TGFβ1, BMP4, Activin-A, and CHIR99021 (“E8BAC medium”) for two days. Preferably, the culture medium comprises or consists essentially of DMEM/F12 medium; L-ascorbic acid-2-phosphate magnesium (64 mg/l); sodium selenium (14 μg/l); human FGF2 (100 μg/l); insulin (20 mg/l); NaHCO₃ (543 mg/l); transferrin (10.7 mg/l); TGFβ1 (2 μg/l); BMP4 (5 μg/l); Activin A (25 μg/l); and CHIR99021 (1 μM). Human pluripotent stem cells are cultured in the culture medium for about two days. After about two days, at least about 80% (e.g., at least about 80%, 85%, 90%, 95%, 99%) of the resulting cell population are mesoderm cells. As used herein, the term “mesoderm cell” refers to a cell having mesoderm-specific gene expression, capable of differentiating into a mesodermal lineage such as bone, muscle such as cardiac muscle, skeletal muscle and smooth muscle (e.g., of the gut), connective tissue such as the dermis and cartilage, kidneys, the urogenital system, blood or hematopoietic cells, heart and vasculature. Mesoderm-specific biomarkers include Brachyury (T). Culturing can take place on any appropriate surface (e.g., in two-dimensional or three-dimensional culture).

As used herein, “pluripotent stem cells” appropriate for use according to a method of the invention are cells having the capacity to differentiate into cells of all three germ layers. Suitable pluripotent cells for use herein include human embryonic stem cells (hESCs) and human induced pluripotent stem (iPS) cells. As used herein, “embryonic stem cells” or “ESCs” mean a pluripotent cell or population of pluripotent cells derived from an inner cell mass of a blastocyst. See Thomson et al., Science 282:1145-1147 (1998). These cells express Oct-4, SSEA-3, SSEA-4, TRA-1-60 and TRA-1-81. Pluripotent stem cells appear as compact colonies comprising cells having a high nucleus to cytoplasm ratio and prominent nucleolus. ESCs are commercially available from sources such as WiCell Research Institute (Madison, Wis.). As used herein, “induced pluripotent stem cells” or “iPS cells” mean a pluripotent cell or population of pluripotent cells that may vary with respect to their differentiated somatic cell of origin, that may vary with respect to a specific set of potency-determining factors and that may vary with respect to culture conditions used to isolate them, but nonetheless are substantially genetically identical to their respective differentiated somatic cell of origin and display characteristics similar to higher potency cells, such as ESCs, as described herein. See, e.g., Yu et al., Science 318:1917-1920 (2007).

Induced pluripotent stem cells exhibit morphological properties (e.g., round shape, large nucleoli and scant cytoplasm) and growth properties (e.g., doubling time of about seventeen to eighteen hours) akin to ESCs. In addition, iPS cells express pluripotent cell-specific markers (e.g., Oct-4, SSEA-3, SSEA-4, Tra-1-60 or Tra-1-81, but not SSEA-1). Induced pluripotent stem cells, however, are not immediately derived from embryos. As used herein, “not immediately derived from embryos” means that the starting cell type for producing iPS cells is a non-pluripotent cell, such as a multipotent cell or terminally differentiated cell, such as somatic cells obtained from a post-natal individual.

Human iPS cells can be used according to a method described herein to obtain AECs having the genetic complement of a particular human subject. For example, it may be advantageous to obtain AECs that exhibit one or more specific phenotypes associated with or resulting from a particular disease or disorder of the particular mammalian subject. In such cases, iPS cells are obtained by reprogramming a somatic cell of a particular human subject according to methods known in the art. See, for example, Yu et al., Science 324(5928):797-801 (2009); Chen et al., Nat. Methods 8(5):424-9 (2011); Ebert et al., Nature 457(7227):277-80 (2009); Howden et al., Proc. Natl. Acad. Sci. U.S.A 108(16):6537-42 (2011). Induced pluripotent stem cell-derived AECs allow modeling of drug responses in tissue constructs that recapitulate vascular tissues in an individual having, for example, a particular disease. Even the safest drugs may cause adverse reactions in certain individuals with a specific genetic background or environmental history. Accordingly, human subject specific iPS cell-derived AECs are useful to identify genetic factors and epigenetic influences that contribute to variable drug responses.

Subject-specific somatic cells for reprogramming into iPS cells can be obtained or isolated from a target tissue of interest by biopsy or other tissue sampling methods. In some cases, subject-specific cells are manipulated in vitro prior to use in a three-dimensional hydrogel-based tissue construct of the invention. For example, subject-specific cells can be expanded, differentiated, genetically modified, contacted to polypeptides, nucleic acids, or other factors, cryo-preserved, or otherwise modified prior to introduction to a three-dimensional tissue construct.

Defined medium and substrate conditions for culturing pluripotent stem cells, as used in the methods described herein, are well known in the art. In some cases, pluripotent stem cells to be differentiated according to the methods disclosed herein are cultured in mTESR-1® medium (StemCell Technologies, Inc., Vancouver, British Columbia), or Essential 8® medium (Life Technologies, Inc.) on a MATRIGEL™ substrate (BD Biosciences, NJ) according to the manufacturer's protocol or on a Corning® Synthemax surface.

Preferably, human pluripotent stem cells (e.g., human ESCs or iPS cells) are cultured in the absence of a feeder layer (e.g., a fibroblast feeder layer), a conditioned medium, or a culture medium comprising poorly defined or undefined components. As used herein, the terms “chemically defined medium” and “chemically defined culture medium” also refer to a culture medium containing formulations of fully disclosed or identifiable ingredients, the precise quantities of which are known or identifiable and can be controlled individually. As such, a culture medium is not chemically defined if (1) the chemical and structural identity of all medium ingredients is not known, (2) the medium contains unknown quantities of any ingredients, or (3) both. Standardizing culture conditions by using a chemically defined culture medium minimizes the potential for lot-to-lot or batch-to-batch variations in materials to which the cells are exposed during cell culture. Accordingly, the effects of various differentiation factors are more predictable when added to cells and tissues cultured under chemically defined conditions. As used herein, the term “serum-free” refers to cell culture materials that do not contain serum or serum replacement, or that contains essentially no serum or serum replacement. For example, an essentially serum-free medium can contain less than about 1%, 0.9%, 0.8%, 0.7%, 0.6%, 0.5%, 0.4%, 0.3%, 0.2%, or 0.1% serum. “Serum free” also refers to culture components free of serum obtained from animal (e.g., fetal bovine) blood or animal-derived materials, which is important to reduce or eliminate the potential for cross-species viral or prion transmission. For avoidance of doubt, serum-containing medium is not chemically defined.

The methods provided herein produce isolated populations of pluripotent stem cell-derived AECs, where the isolated population is a substantially pure population of AECs. As used herein, “isolating” and “isolated” refer to separating, selecting, or enriching for a cell type of interest or subpopulation of cells from surrounding, neighboring, or contaminating cells or from cells of another type. As used herein, the term “substantially pure” refers to a population of cells that is at least about 80% (e.g., at least about 80%, 82%, 83%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or more) pure, with respect to AECs making up a total cell population. In other words, the term “substantially pure” refers to a population of AECs of the present invention that contains at least about 80% (e.g., at least about 80%, 82%, 83%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or more) of AECs when directing differentiation to obtain cells of the arterial endothelial cell lineage. The term “substantially pure” also refers to a population of AECs of the present invention that contains fewer than about 20%, about 10%, or about 5% of non-AECs in an isolated population prior to any enrichment, expansion step, or differentiation step. In some cases, a substantially pure isolated population of AECs generated according to a method provided herein is at least about 95% (e.g., at least about 95%, 96%, 97%, 98%, 99%) pure with respect to AECs making up a total cell population.

An important difference between arterial endothelial cells produced from iPS cells from a specific individual and primary arterial endothelial cells isolated from that same individual is that the iPS cell-derived cells are infinitely scalable and are capable of exceeding the Hayflick limit (a certain number of cell divisions). As used herein, the term “Hayflick limit” refers to a finite number of population doublings in vitro before a cell can no longer proliferate and enters senescence (Hayflick L. Exp Cell Res 37:614-36, 1965). While the inherent self-renewal capacity of primary cultured arterial endothelial cells is limited, an almost inexhaustible supply of arterial endothelial cells can be obtained according to the methods provided herein from a single source (e.g., a somatic cell of an individual). Accordingly, in an embodiment of the invention, the AECs are capable of expansion within the tissue culture laboratory such that the numbers of cells obtained is sufficient to treat more than one patient and, in the preferred embodiment, are capable of cell banking.

In some embodiments, the proportion of arterial endothelial cells in a population of cells obtained in the described methods is enriched using a cell separation, cell sorting, or enrichment method, e.g., fluorescence activated cell sorting (FACS), enzyme-linked immunosorbent assay (ELISA), magnetic beads, magnetic activated cell sorting (MACS), laser-targeted ablation of non-endothelial cells, and combinations thereof. Preferably, FACS is used to identify and separate cells based on cell-surface antigen expression.

The methods of the present invention provide scalable, inexpensive, and reproducible generation of human ABCs. For instance, after obtaining a cell population comprising human AECs according to a method described herein, the human AEC population can be expanded in a culture medium appropriate for proliferating human AECs including, without limitation, Human Endothelial Serum-Free Medium (Life Technologies, Cat. No. 11111-044), EGM-2 (Lonza, Cat. No. CC-3162), and Endothelial Cell Culture Medium (BD Biosciences, Cat. No. 355054).

TABLE 1 Chemically Defined Culture Medium Components Medium Chemically Defined Name Protocol Step Components E8 DMEM/F12 medium + L-ascorbic acid-2-phosphate magnesium (64 mg/l); sodium selenium (14 μg/l); human FGF2(100 μg/l); insulin (20 mg/l); NaHCO₃ (543 mg/l); Transferrin (10.7 mg/l); and TGFβ1 (2 μg/l) E8BAC Human pluripotent stem E8 medium + cells to mesodermal cells BMP4 (5 μg/l); Activin A (25 μg/l); and CHIR99021 (1 μM) E7 DMEM/F12 medium + L-ascorbic acid-2-phosphate magnesium (64 mg/l); sodium selenium (14 μg/l); human FGF2 (100 μg/l); insulin (20 mg/l); NaHCO₃ (543 mg/l); and Transferrin (10.7 mg/l) E7BVi E7 medium + VEGFA (50 μg/l); BMP4 (50 μg/l); and SB431542 (5 μM) E7Bi E7 medium + BMP4 (50 μg/l); and SB431542 (5 μM) E7Vi E7 medium + VEGFA (50 μg/l); and SB431542 (5 μM) E7V E6 medium + FGF2 (100 ng/ml); and 50 ng/ml VEGFA E6 DMEM/F12 medium + L-ascorbic acid-2-phosphate magnesium (64 mg/l); sodium selenium (14 μg/l); insulin (20 mg/l); NaHCO₃ (543 mg/l); and transferrin (10.7 mg/l) E6FVB E6 medium + human FGF2(100 μg/l); VEGFA (50 μg/l); and BMP4 (50 μg/l) E6V E6 medium + VEGFA (50 μg/l) E5 DMEM/F12 medium + L-ascorbic acid-2-phosphate magnesium (64 mg/l); sodium selenium (14 μg/l); NaHCO₃ (543 mg/l); and transferrin (10.7 mg/l) FVIRL Differentiating E5 medium + pluripotent stem cell- Human FGF2 (100 μg/l) derived mesodermal VEGF-165 (50 μg/l) cells into arterial SB431542 (10 μM) endothelial cells RESV (5 μM) L-690,330 (10 μM) FVIRLW FVIRL + WNT3A (100 ng/ml) FVIRL-5 E5 medium + Human FGF2 (100 μg/l); VEGF-165 (50 μg/l); SB431542 (10 μM); RESV (5 μM); and L-690,330 (5 μM) FVIRL-5-I FVIRL-5 + insulin (20 mg/l) FVIRL-5-W FVIRL-5 + WNT3A (50 ng/ml) FVIRL-5-BB FVIRL-5 + PDGF-BB (100 ng/ml) FVIR Maintaining and E5 medium + expanding arterial Human FGF2 (100 μg/l); endothelial cells VEGF-165 (50 μg/l); SB431542 (10 μM); and RESV (5 μM) FVIL E5 medium + Human FGF2 (100 μg/l); VEGF-165 (50 μg/l); SB431542 (10 μM); and L-690,330 (10 μM) FVIW E5 medium + Human FGF2 (100 μg/l); VEGF-165 (50 μg/l); SB431542 (10 μM); and WNT3A (100 ng/ml) FVB E5 medium + Human FGF2 (100 μg/l); VEGF-165 (50 μg/l); and BMP4 (50 μg/l) FVI E5 medium + Human FGF2 (100 μg/l); VEGF-165 (50 μg/l); and SB431542 (10 μM) FV E5 medium + Human FGF2 (100 μg/l) VEGF-165 (50 μg/l) BVIn Differentiating E5 medium + pluripotent stem cell- BMP4 (50 μg/l); derived mesodermal VEGF-165 (50 μg/l) cells into endothelial Insulin (20 mg/l) cells VI E5 medium + VEGF-165 (50 μg/l) SB431542 (5 μM) Control E5 medium Human FGF2 (100 μg/l) SB431542 (10 μM) Control + Control medium + VEGF VEGF-165 (50 ng/ml) Control + Control medium + RESV RESV (5 μM) Control + Control medium + WNT3A WNT3A (50 ng/ml)

In another aspect, provided herein are therapeutic compositions including arterial endothelial cells obtained according to methods provided herein and methods of using them for the treatment of subjects.

In a further aspect, therefore, the present invention provides methods and compositions for cell transplantation, cell replenishment, and cell or tissue replacement and enhancing vasculogenesis. The method can comprise providing to a subject in need thereof a therapeutically effective amount of arterial endothelial cells derived according to a methods provided herein, whereby providing arterial endothelial cells treats the subject. Disorders requiring cell or tissue replacement and improving vasculogenesis include, without limitation, myocardial and peripheral vascular ischemia, other peripheral artery diseases, myocardial infarction (MI), stroke, and diabetic neuropathy, and any other disorder or disease for which the stricken individual would benefit from angiogenic regenerative medicine. Preferred individual subjects according to the present invention are mammals including, without limitation, humans and non-human primates, as well as canines, felines, ovines, porcines, equines, and bovines. In some cases, a substantially pure population of arterial endothelial cells is obtained using a pluripotent cell (e.g., induced pluripotent stem cell) of the subject in need of treatment. However, a substantially pure population of arterial endothelial cells also can be obtained using pluripotent stem cells of, preferably, a syngeneic or allogeneic donor. Less preferably, a xenogeneic donor is used.

In another aspect, this document provides methods for improving vascular perfusion. In particular, provided herein is a method for treating peripheral arterial disease in a patient, where the method comprises administering to the patient a therapeutic dose of arterial endothelial cells obtained as described herein. As used herein, the term “peripheral arterial disease” refers to acute and chronic critical limb ischemia and ischemia associated with a disorder affecting blood supply to tissues such as diabetes or arteriosclerosis. In some cases, arterial endothelial cells obtained according to the methods provided herein are directly injected into the patient subject to treat the peripheral artery disease. Without being bound to any particular theory, it is expected that such arterial endothelial cells would be therapeutic for limb ischemia (e.g., ischemia associated with diabetes or cardiac infarcts) and more beneficial than treatment with a non-arterial endothelial cell. In exemplary embodiments, in vitro-derived AECs are patient specific or HLA-matched cells for transplantation to a patient to treat ischemia. For example, AECs can be derived from iPS cells obtained by reprogramming a somatic cell of the patient to pluripotency and then using the iPS cells according to a method provided herein to obtain a population comprising patient specific AECs. AECs obtained from patient-derived iPS cells can be administered to the patient in any pharmaceutically acceptable carrier, buffer, or excipient. The route of administration of the cells to the patient may be via intravenous or intramuscular injection. In some cases, for example, AECs derived from human pluripotent stem cells are resuspended in a saline solution and injected intramuscularly at one or more sites of limb ischemia.

Any appropriate dosage can be used for a therapeutic method provided herein. The cell dose will depend on the extent and severity of the ischemia but a preferred range is from about 1×10⁸ cells/patient to about 1×10¹⁰ cells/patient per dose. In some cases, AECs obtained as described herein are co-administered to a subject with other cell types including, for example, smooth muscle cells (e.g., vascular smooth muscle cells).

After administering the cells into the subject, the effect of the treatment method may be evaluated, if desired, using any appropriate method known to practitioners in the art. The treatment may be repeated as needed or required. Following treatment according to the methods provided herein, the treated subject can be monitored for any positive or negative changes in limb ischemia. In a preferred embodiment, a therapeutic increase in blood supply to an ischemic tissue is a result of an increase in blood vessel formation (angiogenesis) following implantation of the said cells. The methods provided herein provide cells that are pro-angiogenic following transplantation. In some cases, positive changes include, without limitation, increased blood supply to ischemic tissue, increased amputation-free survival, decreased need for limb amputation, decreased limb pain when the subject is a rest, and improvements in pain-free walking (e.g., pain-free walking over greater distances).

In another aspect, AECs obtained according to the methods provided herein are useful for methods in which the production of nitric oxide (NO) has a therapeutic or preventative benefit for a subject. For example, provided herein is a method for administering AECs to a subject as a method for providing NO to the subject, whereby administering the AECs treats or prevents atherosclerosis, reduces DNA damage, and/or relaxes smooth muscle cells to improve blood vessel function.

Administration of a therapeutically effective amount of AECs into the recipient subject is generally effected using methods well known in the art, and usually involves directly injecting or otherwise introducing a therapeutically effective AECs into the subject using clinical tools known to those skilled in the art (e.g., U.S. Pat. Nos. 6,447,765; 6,383,481; 6,143,292; and 6,326,198). For example, introduction of AECs of the present invention can be effected locally or systemically via intravascular administration, such as intravenous, intramuscular, or intra-arterial administration, intraperitoneal administration, and the like. Cells can be injected into an infusion bag (e.g., Fenwal infusion bag (Fenwal, Inc.)) using sterile syringes or other sterile transfer mechanisms. The cells can then be immediately infused via IV administration over a period of time, such as 15 minutes, into a free flow IV line into the patient. In some embodiments, additional reagents such as buffers or salts are provided to the recipient subject concurrently with the cells.

In exemplary embodiments, AECs of the present invention are provided to the subject as a pharmaceutical composition comprising the cells and one or more pharmaceutically acceptable carriers, buffers, or excipients. The pharmaceutical composition for administration must be formulated, produced, and stored according to standard methods that provide proper sterility and stability. A pharmaceutical composition of the present invention may also comprise one or more growth factors or cytokines (e.g., angiogenic cytokines) that promote the survival or engraftment of transplanted cells, promote angiogenesis, modulate the composition of extracellular or interstitial matrix, and/or recruit other cell types to the site of transplantation.

In another aspect, provided herein is a method for producing an engineered blood vessel using arterial endothelial cells obtained according to a method provided herein. AECs also can be used as raw materials, optionally in combination with additional cell populations, for creating blood vessels in vitro or in vivo. Such vessels will be useful, for example, in revascularizing damaged tissues and in treating peripheral artery disease. Engraftment of and vasculogenesis by externally injected cells has been shown by in vivo animal studies. See, for example, Kim et al., J. Am. Coll. Cardiol. 56:593-607 (2010).

Also provided herein are methods of using in vitro-derived AECs for in vitro blood vessel formation and for vascularization of engineered tissues that lack a vascular network such as engineered cardiac muscle tissue or heart. For example, AECs are useful in methods for producing tissue-engineered vascular grafts for clinical applications such as replacing diseased vessels. In some cases it will be advantageous to use patient-specific or HLA matched AECs for methods of treating a patient with a tissue-engineered vascular graft, an in vitro-produced blood vessels, or other vascularized engineered tissue. As described above, AECs can be derived from iPS cells obtained by reprogramming a somatic cell of the patient to pluripotency and then using the iPS cells according to a method provided herein to obtain a population comprising patient-specific AECs. In some cases, it will be advantageous to co-culture the AECs with other cell types such as vascular smooth muscle cells (VSMC) to obtain a vascularized engineered tissue construct such as an engineered blood vessel for clinical application such as bypass surgery. Preferably, AECs are combined with patient-specific in vitro-derived vascular smooth muscle cells for these methods. Vascular smooth muscle cells are positive for expression of ACTA2, TAGLN, MYH11, and ELN, but CD31 negative. In other cases, AECs can be co-cultured with cardiomyocytes to form a vascularized cardiac tissue patch useful for improving cardiac function.

In a further aspect, provided herein is a method of in vitro screening of an agent. For example, provided herein are methods of using in vitro-derived arterial endothelial cells for high throughput screening of candidate. For example, AECs obtained as described herein can be screened to identify agents that decrease leukocyte adhesion as a potential therapeutic or preventative for atherosclerosis. Screening methods can comprise or consist essentially of (a) contacting a test agent to an arterial endothelial cell or population of arterial endothelial cells obtained as described herein; and (b) detecting an effect of the agent on the cell or cells (e.g., decreased leukocyte adhesion to AECs). In some cases, screening methods include screening candidate compounds to identify test agents that promote the development of vascular tissue. In other cases, candidate compounds can be screened for toxicity to human arterial endothelial cells or vascular tissue. In some cases, detecting comprises detecting at least one positive or negative effect of the agent on morphology or life span of cells, whereby an agent that increases or reduces the life span of the cells or has a positive or negative impact on the morphology of the cells is identified as having an effect on human arterial endothelial cells or vascular tissues. In some cases, detecting comprises performing a method selected from the group consisting of adhesion assays, RNA sequencing, gene expression profiling, transcriptome analysis, metabolome analysis, detecting reporter or sensor, protein expression profiling, Forster resonance energy transfer (FRET), metabolic profiling, and microdialysis. The agent can be screened for an effect on gene expression, and detecting can comprise assaying for differential gene expression relative to an uncontacted cell or cell population.

In exemplary embodiments, detecting and/or measuring a positive or negative change in a level of expression of at least one gene following exposure (e.g., contacting) of a test compound to arterial endothelial cells comprises whole transcriptome analysis using, for example, RNA sequencing. In such cases, gene expression is calculated using, for example, data processing software programs such as Light Cycle, RSEM (RNA-seq by Expectation-Maximization), Excel, and Prism. See Stewart et al., PLoS Comput. Biol. 9:e1002936 (2013). Where appropriate, statistical comparisons can be made using ANOVA analyses, analysis of variance with Bonferroni correction, or two-tailed Student's t-test, where values are determined to be significant at P<0.05. Any appropriate method can be used to isolate RNA or protein from neural constructs. For example, total RNA can be isolated and reverse transcribed to obtain cDNA for sequencing.

Test compounds can be dissolved in a solvent such as, for example, dimethyl sulfoxide (DMSO) prior to contacting to AECs provided herein. In some cases, identifying agents comprises analyzing the contacted AECs for positive or negative changes in biological activities including, without limitation, gene expression, protein expression, cell viability, and cell proliferation. For example, microarray methods can be used to analyze gene expression profiles prior to, during, or following contacting the plurality of test compounds to the AECs. In some cases, a method of the present invention further comprises additional analyses such as metabolic assays and protein expression profiling.

Compositions

In another aspect, provided herein are preparations of AECs. For example, provided herein are AECs, substantially purified populations of AECs, pharmaceutical preparations comprising AECs, and cryopreserved preparations of the AECs. The AECs described herein may be substantially free of at least one protein, molecule, or other impurity that is found in its natural environment (e.g., “isolated”). The AECs may be mammalian, including, human AECs. The invention also provides human AECs, a substantially purified population of human AECs, pharmaceutical preparations comprising human AECs, and cryopreserved preparations of the human AECs. The preparation may be a preparation comprising human embryonic stem cell-derived AECs, human iPS cell-derived AECs, and substantially purified (with respect to non-AECs) preparations comprising differentiated pluripotent stem cell-derived AECs.

Cell preparations provided herein are useful for various in vitro and in vivo applications such as engineering new blood vessels, endothelial cell transplantation into the heart for myocardial regeneration, induction of angiogenesis for treatment of regional ischemia, and screening for drugs affecting vasculature such as angiogenesis inhibition to slow cancer progression. Since most vascular disease occurs in arteries (Go et al., 2014), arterial cells are extremely valuable for disease modeling, as they can be used for investigating how arterial endothelial cells are activated, and for screening drugs to prevent the activation, which will facilitate understanding and curing atherosclerosis. Because it has been very difficult to obtain AECs, these cells have been largely omitted from tissue-engineered vascular grafts and pre-vascularization of tissue transplants (Bae et al., 2012; Campbell and Campbell, 2007), which could contribute to poor clinical outcome. The disclosed methods facilitate production and use of AEC populations.

Preparations comprising AEC cells useful for clinical applications must be obtained in accordance with regulations imposed by governmental agencies such as the U.S. Food and Drug Administration. Accordingly, in exemplary embodiments, the methods provided herein are conducted in accordance with Good Manufacturing Practices (GMPs), Good Tissue Practices (GTPs), and Good Laboratory Practices (GLPs). Reagents comprising animal derived components are not used, and all reagents are purchased from sources that are GMP-compliant. In the context of clinical manufacturing of a cell therapy product, such as in vitro populations of human arterial endothelial cells, GTPs govern donor consent, traceability, and infectious disease screening, whereas the GMP is relevant to the facility, processes, testing, and practices to produce a consistently safe and effective product for human use. See Lu et al. Stem Cells 27: 2126-2135 (2009). Where appropriate, oversight of patient protocols by agencies and institutional panels is envisioned to ensure that informed consent is obtained; safety, bioactivity, appropriate dosage, and efficacy of products are studied in phases; results are statistically significant; and ethical guidelines are followed.

In another aspect, provided herein is a culture medium or a culture system comprising a culture medium for differentiating human pluripotent stem cell-derived mesodermal cells into AECs, where the culture medium comprises or consists essentially of a Fibroblast Growth Factor (FGF), a vascular endothelial growth factor (VEGF), an inhibitor of TGF-beta signaling (e.g., SB431542), a Notch agonist (e.g., Resveratrol (RESV)), and an inhibitor of inositol monophosphatase. In exemplary embodiments, the culture medium comprises or consists essentially of E5 medium supplemented with human FGF2 (100 μg/l), VEGF-165 (50 μg/l), SB431542 (10 μM), RESV (5 μM), and L-690,330 (10 μM). Such a culture medium does not comprise insulin.

Articles of Manufacture

The invention also provides a kit for differentiating human pluripotent stem cells into AECs, comprising (i) a first culture medium suitable for differentiation of human pluripotent stem cells into mesodermal cells; (ii) a second culture medium suitable for differentiation of pluripotent stem cell-derived mesodermal cells into arterial endothelial cells; and (iii) instructions describing a method for differentiating human pluripotent stem cells into CD31⁺/CD144⁻/CD41⁻/CD45⁻ arterial endothelial cells, the method employing the first culture medium and the second culture medium.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs. Although any methods and materials similar to or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods and materials are described herein.

In the specification and in the claims, the terms “including” and “comprising” are open-ended terms and should be interpreted to mean “including, but not limited to . . . .” These terms encompass the more restrictive terms “consisting essentially of” and “consisting of.” As used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural reference unless the context clearly dictates otherwise. As well, the terms “a” (or “an”), “one or more” and “at least one” can be used interchangeably herein. It is also to be noted that the terms “comprising,” “including,” “characterized by,” and “having” can be used interchangeably.

As used herein, “a medium consisting essentially of” means a medium that contains the specified ingredients and those that do not materially affect its basic characteristics.

As used herein, “effective amount” means an amount of an agent sufficient to evoke a specified cellular effect according to the present invention.

As used herein, “about” means within 5% of a stated concentration range, density, temperature, or time frame.

The invention will be more fully understood upon consideration of the following non-limiting Examples. It is specifically contemplated that the methods disclosed are suited for pluripotent stem cells generally. All papers and patents disclosed herein are hereby incorporated by reference as if set forth in their entirety.

EXAMPLES Example 1—Protocol for Directed Differentiation of Pluripotent Stem Cells into AECs

To investigate arterial differentiation, an endothelial cell differentiation protocol was developed using a defined culture medium lacking both serum and bovine serum albumin. Xeno-free pluripotent stem cells were first differentiated into mesoderm cells in a culture medium supplemented with BMP4, Activin-A, and CHIR99021 (E8BAC medium) for two days. Mesoderm cells were then treated with FGF2, VEGFA, and BMP4 for another three days, yielding a 70% CD31⁺/CD34⁺ endothelial cell population (FIGS. 2A-B). Insulin was included in this mesoderm-to-endothelium differentiation medium. Endothelial cell fate was further confirmed by the down-regulation of NANOG and OCT4 (FIG. 2C), the up-regulation of KDR/VEGFR2, the expression of CD144 (CDHS/VE-cadherin) (FIG. 2D), the internalization of LDL (FIG. 2E), and the formation of capillary networks in vitro and in vivo (FIGS. 2F-G). With this protocol, we were able to investigate the effect of individual medium components under completely defined culture conditions (FIG. 2H).

Since cells of the CD31⁺/CD34⁺ endothelial cell population largely failed to express markers of AECs (data not shown), we isolated a population of CD31⁺/CD144⁺/CD41⁻/CD45⁻ endothelial cells from the aorta-gonad-mesonephros (AGM) region of embryonic mesoderm of a E11.5 day mouse embryo. These cells were isolated from the AGM to identify new factors having capacity to induce arterial differentiation.

Single-cell RNA-Seq was performed for the CD31⁺/CD144⁺/CD41⁻/CD45⁻ endothelial cells to characterize global gene expression profiles of individual endothelial cells. To distinguish arterial and venous endothelial cell populations, a set of arterial markers (Efnb2, Cxcr4, Dll4, Gja4, Hey1, Jag1, Notch1, Notch4, and Nrp1) and venous markers (Aplnr, Ephb4, Flt4, Nr2f2, and Nrp2) were analyzed using SINGuLAR™ Analysis Toolset. Many of the markers clustered into either the arterial group or venous group, but Aplnr and Notch1 did not cluster with either group (FIG. 1A). This result is consistent with a previous study suggesting that some arteriovenous markers are transiently non-specific (Chong et al., 2011). Based on marker expression, the CD31⁺/CD144⁺/CD41⁻/CD45⁻ endothelial cells were clustered into five subpopulations (FIG. 1A). The average normalized expression of arterial and venous gene sets within each subpopulation was calculated to distinguish arterial and venous cells (FIG. 1B). Population 1 (P1) was identified as arterial endothelial cells, as it had the highest arterial and the lowest venous marker expression (FIG. 1B). By contrast, Population 3 (P3) had the lowest arterial gene expression (FIG. 1B). Principal component analysis revealed a clear separation between the P1 and P3 cells (FIG. 1C), and 918 genes were determined to be enriched in P1 cells (arterial endothelial cells) (p<0.1, FC>2, T1VIP>1) compared to P3 cells (see Table 4).

To identify growth factor related genes within the 918 arterial enriched genes, five AmiGo gene ontology data “terms” were combined: growth factor binding (GO:0019838), growth factor activity (GO:0008083), growth factor receptor binding (GO:0070851), receptor activity (GO:0004872), and receptor binding (GO:0005102). The combined list was then intersected with plasma membrane genes (GO:0005886) to remove non-cell surface genes (FIG. 1D and Tables 2 and 4). Some of the resulting 42 genes were not growth factors or their receptors, but were either upstream or downstream of a growth factor signaling pathway. Some well-known arteriovenous regulators, including VEGFA, Wnt signaling (FZD4, FZD7, FZD10), and Notch signaling (DLL4 and Notch4) were present in these 42 genes (Table 2).

In order to test candidate factors in human arterial differentiation, we made a dual human ES cell reporter line using clustered regularly interspaced short palindromic repeats (CRISPR (clustered regularly interspaced short palindromic repeats)-Cas9 technology to target EFNB2 (ephrin B2) with tdTomao and EPHB4 (ephrin type B receptor 4) with EGFP (FIGS. 8A-8B). See, e.g., Hou et al., 2013. EFNB2 and EPHB4 are the most characterized embryonic arterial and venous endothelial cell markers, respectively (Wang et al., 1998). Specific targeting of the EFNB2 and EPHB4 loci was confirmed by junction PCR and southern blot (FIGS. 8C-8F). Only single copies of each reporter were integrated into genome (FIGS. 8G-8H), and the endogenous expression of EFNB2 and EPHB4 in the reporter cell line was similar to that in wild type cells (FIG. 81 ). Karyotypes were normal after dual targeting (FIGS. 8J), and DNA sequencing revealed no CRISPR induced insertions or deletions in the wild type alleles.

We used the EFNB2-tdTomato/EPHB4-EGFP dual reporter cell line to test the function of individual growth factor related genes identified by single-cell RNA-Seq analysis. Consistent with their previously described roles, VEGFA, WNT3A, and RESV (a Notch agonist) all promoted increased arterial specification (FIG. 11 ).

We then investigated the other growth factors/signaling pathways during endothelial cell differentiation by adding or removing recombinant proteins/small molecules, such as insulin, as it is widely used in endothelial cell differentiation protocols. Surprisingly, removing insulin after mesoderm formation triggered AEC differentiation, as evidenced by the increased number of EFNB2-tdTomato^(high)/EPHB4-EGFP^(low) cells (FIGS. 3A-B). Since insulin is able to activate AKT (Mackenzie and Elliott, 2014), a negative regulator of arteriovenous specification (Hong et al., 2006), we examined AKT activity. Phosphorylated AKT (pAKT) was increased by the presence of insulin, and inhibiting PI3K activity using Ly294002 (a reversible inhibitor of phosphoinositide 3-kinases (PI3Ks)) decreased pAKT (FIG. 3C) and reversed the inhibitory effect of insulin during arterial differentiation (FIGS. 3A-3B). These results demonstrate that the insulin-AKT pathway played a key role in suppressing arterial differentiation.

In addition, we found that the following factors increased arterial endothelial cell differentiation: FGF2, L-690,330 (a inositol monophosphatase inhibitor), and LDL (low-density lipoprotein), as evidenced by the increase of EFNB2-tdTomato^(high)/EPHB4-EGFP^(low) cells (FIG. 3F). In contrast, removing SB431542 (a TGF-β receptor inhibitor) or adding PDGF-BB inhibited arterial differentiation (FIGS. 3E-3F).

To further confirm these results, EFNB2-tdTomato^(high)/EPHB4-EGFP^(low) putative arterial endothelial cells and EFNB2-tdTomato^(low)/EPHB4-EGFP^(high) putative venous endothelial cells were sorted by FACS and analyzed by RT-qPCR. Arterial genes were significantly up-regulated in EFNB2-tdTomato^(high)/EPHB4-EGFP^(low) cells. These data demonstrate that FGF, L-690,330, and LDL promote arterial endothelial differentiation of human pluripotent stem cells while insulin, TGF-β, and PDGF inhibit arterial endothelial differentiation.

To further improve arterial differentiation, we examined combinations of individual factors. Arterial endothelial cell differentiation was greatly improved by combining FGF, VEGFA, SB431542, RESV, and L-690,330 (“five factors”) in a chemically defined medium (‘FVIRL medium” in Table 1; see also FIGS. 4A-4B) when compared to the differentiation observed when single factors were employed. Removing FGF, VEGF, SB431542, or RESV individually led to a decrease of EFNB2-tdTomato^(high)/EPHB4-EGFP^(low) cells (FIGS. 4A-4B). Two other arterial markers, CXCR4 and DLL4, were similarly decreased upon removal of FGF, VEGF, SB431542, or RESV (FIGS. 4C-4F). However, when RESV or L-690,330 was removed, or when PDGF as added, fewer EFNB2-tdTomato^(high)/EPHB4-EGFP^(low) putative arterial endothelial cells were obtained, but no reduction of CD144⁺CXCR4⁺ and CD144⁺DLL4⁺ cells was observed (FIGS. 4C-4F). Although as a single factor WNT3A promoted arterial differentiation, exogenous WNT3A did not further increase arterial differentiation in the context of the other five factors (FIGS. 4A-4F, FIG. 9 ).

Endothelial cells generated with the five-factor protocol took up LDL, formed vascular networks, and maintained EFNB2 (Ephrin B2) expression in those networks (FIGS. 5C-5D). Another characteristic feature of functional AECs is decreased leukocyte adhesion relative to that of venous endothelial cells (Hauser et al., J Immunol 151, 5172-5185 (1993); Kalogeris et al., Am J Physiol 276, L9-L19 (1999)). Thus, we analyzed the ability of TNFα, a pro-inflammatory cytokine to induce leukocyte adhesion in different types of endothelial cells (De Caterina et al., 1995).

Finally, we examined whether the human ES cell-derived AECs exhibit arterial-specific functional characteristics. First, the “five factors” AECs produced NO at levels comparable to primary human coronary arterial endothelial cells (HCAECs), and at higher levels than HUVEC cells (FIG. 7A). Second, AECs consumed oxygen at rates similar to primary arterial endothelial cells, and at higher rates than HUVEC cells (FIG. 7B). Third, the AECs elongated in response to shear stress to a similar degree as primary arterial endothelial cells, and to a greater degree than HUVEC cells (FIGS. 7C-7D). The AECs exhibited low levels of TNFα-induced leukocyte adhesion (Hauser et al., J Immunol 151, 5172-5185 (1993); Kalogeris et al., Am J Physiol 276, L9-L19 (1999)) that was comparable to primary arterial endothelial cells and was much lower than that of HUVEC cells (FIGS. 7E-7F). In summary, our combined results demonstrate that the AECs are characterized by gene expression and functional properties, which are distinct from venous endothelial cells but consistent with arterial endothelial cells.

Previous studies revealed that the vascular smooth muscle expressed ACTA2 (smooth muscle actin or “SMA”), TAGLN (Smooth muscle protein 22-alpha or “SM22A”), MYH11 (myosin, heavy chain 11, smooth muscle), and elastin (ELN). Owens et al., Physiol Rev 84, 767-801 (2004). We further demonstrated that CD31 could be used to distinguish intestinal and vascular smooth muscle cells. As shown in FIG. 12 , MYH11-positive vascular smooth muscle is recruited to the blood vessels. In the intestine, smooth cells express both MYH11 and CD31 (arrow indicated), demonstrating that MYH11⁺CD31⁻ cells are vascular smooth muscle cells while MYH11⁺CD31⁺ cells are intestinal smooth muscle cells.

TABLE 2 Arterial Enriched Growth Factor Related Genes Related Pathway Gene Description Treatment Adiponectin ADIPOR2 Adiponectin receptor protein 2 Add adiponectin (ADIPO) Angiopoietin ANGPT2 Angiopoietin-2 Add ANGPT2 BMP CRIM1 Cysteine-rich motor neuron 1 protein. Remove BMP4 Antagonist of BMP4/7 Chemerin CMKLR1 Chemokine-like receptor 1 Add Chemerin EFNA1 EFNA1 Ephrin-A1. Positively regulated by TNF Add TNF or VEGF and VEGF EFNB2 EFNB2 Ephrin-B2. Arterial endothelial cell N/A marker EGF and VEGF related LDLR Low-density lipoprotein receptor. Add EGF or VEGFA Positive regulation of KDR and EGF EGF and VEGF related SSFA2 Sperm-specific antigen 2. Positively Add EGF or VEGFA regulated by KRAS, which can be activated by EGF and VEGF EGF related CELSR1 Cadherin EGF LAG seven-pass G-type Add EGF receptor 1. Interacts with EGFR EGF related CD2AP CD2-associated protein. Interacts with Add EGF EGFR EGF related CD9 CD9 antigen. Binds to EGF Add EGF EGF related THBD Thrombomodulin. Positive regulation of Thrombomodulin (THBD) EGFR FGF FGFR2 Fibroblast growth factor receptor 2 Add FGF2 FGF related ARRB2 Beta-arrestin-2. FGFR1 recruits ARRB2 Add FGF2 upon agonist treatments IFN IFNGR2 Interferon gamma receptor 2 Add IFNg Insulin/IGF IGFBP3 Insulin-like growth factor 2 mRNA- Add insulin binding protein 3. Inhibits IGF pathway Interleukin IL13RA1 Interleukin-13 receptor subunit alpha-1 Add IL13 LIF STAT3 Signal transducer and activator of Add LIF transcription LIF or Wnt related YES1 Tyrosine-protein kinase Yes. Regulated Add LIF or Wnt by LIF and Wnt NGF PTPRG Receptor-type tyrosine-protein Add B-NGF to reverse its phosphatase gamma. Inhibits NGF effects function Notch DLL4 Delta-like protein 4 NOTCH signaling, previously reported Notch NOTCH1 Neurogenic locus notch homolog protein NOTCH signaling, 1 previously reported Notch related APLP1 Amyloid-like protein 1. Processed by γ- Add APLP1 secretase, which is also part of Notch signaling Notch related PALM Paralemmin-1. Overexpressed in ESR1+ Add PALM breast cancer cells. Notch actives ESR dependent transcription Notch related DAG1 Dystroglycan: acts downstream of Notch Add DAG1 signaling pathway NPR NPR2 Atrial natriuretic peptide receptor 2 Add C-type natriuretic peptide PDGF related SLC9A3R2 Na(+)/H(+) exchange regulatory Increase PDG-BB activity, cofactor NHE-RF2 so add PDGF-BB PDGF related ABCA1 ATP-binding cassette sub-family A Add PDGF-BB to suppress it member 1. Suppressed by PDGF SDF CXCR4 C-X-C chemokine receptor type 4 Add CXCL12/SDF Semaphorin PLXNA2 Plexin-A2 Add Semaphorin (SEMA) Slit ROBO2 Roundabout homolog 2; response to slit Add Slit2-N ligand TGF BRCA1 Breast cancer type 1 susceptibility Add or remove SB431542 protein; expression is inhibited by (TGF receptor inhibitor) TGFβ1. TNF SLC20A1 Sodium-dependent phosphate transporter Add TNFα 1. Upregulated by TNF VEGF VEGFA VEGF signaling, previously reported VEGF related GRIA2 Glutamate receptor 2, GluR2, Add GlutaMAX ™ medium upregulated by VEGF (Glu) VEGF related LEPR Leptin receptor. Leptin upregulates Add LEPTIN VEGF signaling VEGF related XPR1 Xenotropic and polytropic retrovirus Add VEGF receptor 1. Binds to ACTR6, which can be activated by VEGF VEGF related INPP5K Inositol polyphosphate 5-phosphatase K. Add L-690,330 (inositol Inositol pathway suppresses VEGF monophosphatase inhibitor) (L690) Wnt FZD4 Frizzled-4 WNT signaling, previously reported Wnt FZD7 Frizzled-7 WNT signaling, previously reported Wnt FZD10 Frizzled-10 WNT signaling, previously reported N/A SLC20A2 Sodium-dependent phosphate transporter N/A 2

Materials and Methods

Isolation of mouse endothelial cells for single-cell RNA-seq: Twenty-four E11.5 mouse (CD-1 background) embryos were harvested. The head, tail, limb, internal organ, and somite were removed. The aorta-gonad-mesonephros (AGM) tissue was incubated in 2 mg/ml collagenase type IV (Life Technologies, cat #17104-019) and 0.25 mg/ml dispase (Life Technologies, cat #17105-041) solution for 15 minutes on ice to let enzyme penetrate into the tissue. The tissue with enzyme was then incubated at 37° C. for 10 minutes. The enzyme was neutralized by 2% FBS-HBSS and pipetted up and down to further dissociate the cells. The cells were immunostained and CD31⁺CD144⁺CD41⁻CD45⁻ endothelial cells were sorted out by flow cytometry. CD41 and CD45 were used to deplete hematopoietic stem cells.

Isolation of human fetus arterial endothelial cells for single-cell RNA-seq: Human fetal aorta tissue (14 weeks gestation) was dissected from the aortic arch to the abdominal bifurcation. Tissue was obtained from the Human Fetal Tissue Repository at Albert Einstein College of Medicine of Yeshiva University (Bronx, NY). This work was done under approval from the UW-Madison Health Sciences IRB and the IRB of Albert Einstein College of Medicine. The adventitia layer of human fetus dorsal aorta was completely removed and the rest of the tissue was cut into small pieces. The tissue was then digested by 300 U/ml collagenase/elastase (Worthington Biochem, cat #LK002067) for one hour at 37° C., and the tissue was pipetted up and down every 20 minutes. The endothelial cells were sorted by flow cytometry using anti-CD31 antibody.

Single cell RNA-sequencing. For mouse AGM cells, 15 μl cell suspension (containing 5×10⁴ cells) was loaded into a Fluidigm C₁™ chip. RNA isolation, cDNA library preparation were performed on Fluidigm C₁™ Single-Cell Auto Prep System as manufacturer suggested (Smarter-seq1 protocol). cDNA concentration was measured by Quant-iT™ PicoGreen® dsDNA assay kit (Life Technology, cat #P7589) and diluted to 0.1-0.3 ng/μl. cDNA was tagmented (by a modified transposition reaction) and barcoded by using Nextera XT DNA Sample Prep Kit (Illumina, cat #FC-131-1024). For sequencing (Illumina, HiSeq2500), 18-24 samples were pooled. In total, 84 cells were sequenced. After doublet exclusion and outlier removing, 70 cells were used for further analysis.

For AECs derived by the “five factors” protocol, CD144⁻/EFNB2-tdTomato^(high)/EPHB4-EGFP^(low) cells were sorted and loaded into a Fluidigm C₁™chip. cDNA were prepared and sequenced as mentioned above. In total, 96 cells were sequenced and used for further analysis.

For primary AECs (“pAECs;” freshly isolated from 14 weeks old human fetus dorsal aorta), smarter-seq2 protocol was applied to Fluidigm C₁™ single-cell auto prep system for cDNA preparation. Smarter-seq2 is has been shown to improve cDNA yield and sequencing sensitivity⁴¹, thus it's suitable for samples with relative low RNA quality. In total, 48 cells were sequenced and used for further analysis.

H1 ES and HUVEC cells were prepared by Fluidigm C₁™ single-cell auto prep system using smarter-seq2 protocol. In total, twenty-four H1 and 48 HUVEC cells were sequenced and used for further analysis.

Hierarchical clustering: Single-cell RNA-seq data (TPM) were generated from RSEM. For each gene, the log 2 TPM was scaled to z scores with mean 0 and variance 1. Prior to taking the logarithm, TPM below 1 was imputed as 1. Hierarchical clustering was performed using the Euclidean distances between cells (FIG. 1 ).

Data analysis by SINGuLAR Analysis Toolset 2.1: Single-cell RNA-seq data (TPM) was loaded to SINGuLAR Analysis Toolset 2.1. The outliers were removed by the “identifyOutliers( )” command. Arterial and venous markers of the samples were them analyzed by the “autoAnalysis( )” command. As a result, PCA plot of FIG. 1C was automatically generated. Heat map of AECs data (FIG. 10 ) was also generated by “autoAnalysis( )” of SINGuLAR.

Principle component analysis by R program: Principle component analysis (PCA) was performed on single-cell RNA-seq data (FIG. 5B). To adjust for sequencing depth variation across different cells, expected counts were normalized by medium-ratio normalization. To reduce the effect of potential outliers, for each gene, values that were greater than the 95th quantile of the gene-specific expression had been imputed using the 95th quantile. Prior to PCA, the gene-specific normalized expression was rescaled to values with mean 0 and standard deviation 1 for all genes. The PCA analysis was performed using prcomp( ) function in R.

Generation of the growth factor related gene list: Five Amigo Go Terms (version 1.8) growth factor binding (GO:0019838), growth factor activity (GO:0008083), growth factor receptor binding (GO:0070851), receptor activity (GO:0004872), and receptor binding (GO:0005102) were combined. The combined list was then joined with plasma membrane (GO:0005886) to generate the growth factor related gene list. The list was further joined with “arterial-enriched genes” from Table 5 to generate an arterial enriched growth factor related gene list of Table 6.

Gene targeting on the H1 ES cells: The 5′ and 3′ homology arms of EFNB2 targeting vector were synthesized by IDT (gBlock) with introducing Sal I and BamH I (5′ arm), Bmt I and Mlu I (3′ arm) restriction sites to facilitate subcloning into the targeting vector. The 5′ and 3′ homology arms of EPHB4 targeting vector were PCR amplified from BAC (bacterial artificial chromosome).

To achieve the best electroporation efficiency, human ES cells (H1) were EDTA passaged (1:4 split) and cultured to reach 80-90% confluence two days before the experiment. At the day of the experiment, ES cells were dissociated by Accutase, washed once with E8 medium, and resuspended at densities of 5×10⁶ cells/mL in E8 medium with 10 mM Hepes buffer (pH 7.2-7.5) (Life Technologies). For electroporation, 400 μL of cell suspension, 7.5 μg gRNA plasmid, 7.5 μg spCas9 plasmid, and 10 μg linearized DNA template plasmid were mixed in a 4-mm cuvette (Bio-Rad) and immediately electroporated with a Bio-Rad Gene Pulser. Electroporation parameters were 250 V, 500 μF, and infinite resistance. Cells were then plated on Matrigel™-coated plate in E8 medium (10 μM Y27632 was added for the first day). For the EFNB2-tdTomatom cell line, 100 μg/ml Geneticin was added to the medium when cells reached to 20% confluence (usually 3-4 days after electroporation) and drug selection was used for the last five days. For the EPHB4-EGFP cell line, 0.5 μg/ml puromycin was added to the medium when cells reached to 20% confluence. Due to the drug sensitivity of cells in E8 medium, eight hours/day puromycin treatment was performed for five days. Surviving colonies were picked four to six days after drug selection and expanded in E8 medium.

Karyotyping: Karyotyping was performed by WiCell Research Institute.

Southern blot: The probe was synthesized by using PCR DIG Probe Synthesis Kit (Roche, Cat #11 636 090 910). The southern blot was performed following DIG Application Manual for Filter Hybridization from Roche.

TABLE 3 Culture Medium Components Five Medium components E8 E8BAC E6 E5 E7V factors DMEM/F12 + + + + + + L-ascorbic acid-2-phosphate + + + + + + magnesium (64 ng/ml) Sodium selenium (14 ng/ml) + + + + + + NaHCO₃ (543 μg/ml) + + + + + + Transferrin (10.7 μg/ml) + + + + + + Insulin (20 μg/ml) + + + + FGF2 (100 ng/ml) + + + + TGFβ1 (2 ng/ml) + + BMP4 (5 ng/ml) + Activin A (25 ng/ml) + CHIR99021 (1 μM) + VEGFA₁₆₅ (50 ng/ml) + + SB431542 (10 μM) + RESV (5 μM) + L690 (10 μM) +

Human pluripotent stem cell culture and differentiation: iPS cell line 005B23.1 was derived from skin punch fibroblast and maintained on recombinant vitronectin-coated plates. DF19.11 was derived from foreskin fibroblast. CD-3-1 was derived from cord blood cells. PBMC was derived from peripheral blood mononuclear cells. H1 and H9 ES cells were derived from male and female embryos, respectively.

Human pluripotent stem cells were cultured in E8 medium on a Matrigel™-coated plate (excepted 005B23.1). To achieve the best differentiation results, ES cells were split by EDTA at 1:4 ratios two days before the differentiation. The cells reached 80-90% confluency two days later. At the day of the differentiation, ES cells were dissociated by Accutase (Invitrogen) for 3 minutes at 37° C. The cells were plated on vitronectin-coated plate (recombined vitronectin, 50 μg/10-cm dish) at 1:3 ratios (1.1-1.5×10⁵ cells/cm 2). The cells reached 100% confluence after 36 hours. To improve cell survival, 101.1M Y27632 was used for the first day. The cells were cultured in E8BAC medium (see Table 3: E8 medium supplemented with 5 ng/ml BMP4, 25 ng/ml Activin A, and 1 μM CHIR99021) for two days. E6 (E8 medium minus FGF2, and TGFβ1) medium supplemented with growth factors or small molecules was then used to induce endothelial cell differentiation for another three days. Medium was changed every day. The cells were harvested at day 5. To isolate CD31⁺CD34⁺ cells, the cells were labeled with CD34 magnetic beads and processed through autoMACS (Miltenyi Biotec). The purified cells were cultured on fibronectin-coated (Life Technologies, Cat #33016-015) (100 μg/10-cm dish) or vitronectin-coated (50 μg/10-cm dish) dishes with E7V (E6+100 ng/ml FGF2+50 ng/ml VEGFA) medium.

Arterial endothelial cell differentiation and expansion: It took six days for AECs differentiation. From day 0 to day 2, human ES/iPS cells were first differentiated into mesoderm cells as mentioned above. From day 2 to day 6, E5 medium was used and growth factors or small molecules were added as indicated. With the combination of “five factors,” AECs were induced by E5 medium supplemented with 100 ng/ml FGF, 50 ng/ml VEGF, 10 μM SB431542, 5 μM RESV, and 10 μM L690 from day 2 to day 6.

AECs were purified by CD144 microbeads (Miltenyi Biotec, cat #130-097-857) for some of the functional assays. After optimization (FIG. 9 ), AECs were maintained in FVIR (E5+100 ng/ml FGF, 50 ng/ml VEGF, 10 μM SB431542, 5 μM RESV) or FVIR+Ins (FVIR medium+10 μg/ml insulin) medium on fibronectin- or vitronectin-coated dishes.

LDL-uptake assay: To perform the LDL-uptake assay, 2 μg/ml acetylated-LDL-FITC was added to the medium and cultured for 4 hours. Ten minutes before imaging, 2 μg/ml Hoechst was added to medium. To co-stain with CD144, anti-CD144-647 antibody was added to medium two hours before imaging. The medium was removed and HBSS was added for live cell imaging. It is important to image the cell in live because fixing the cell will diminish LDL-FITC signal.

MATRIGEL™ encapsulation assay: 1.5×10³ endothelial cells/pi and 0.75×10³ pericytes/μl (ScienCell, cat #1200) were encapsulated in 6.5 mg/ml Matrigel™. A 10 μL Matrigel™/cell solution was spotted in the middle of 24-well plate and incubated for 5 mins at 37° C. for solidification. E7V medium was then applied. Immunostaining was performed on day 4 and the structures were imaged using Nikon confocal microscopy.

In vivo MATRIGEL™ plug angiogenesis assay: 5×10⁵ endothelial cells were resuspended in 100 μl E7V medium and 200 μL Matrigel and then the 300 μL cell/Matrigel™ mixture was subcutaneously injected into the neck of nude mice. After two weeks of inoculation, the Matrigel™ was harvested, fixed, and immunostained. For dextran injection, 100 μg rhodamine-conjugated dextran was retro-orbital injected into mice after four weeks of inoculation. Ten minutes after dextran injection, the Matrigel™ plug was harvested, fixed, and immunostained.

Fibrin Gel Encapsulation Assay: 1.5×10³ endothelial cells/pi and/or 0.75×10³ pericytes/μl were encapsulated in fibrin gel. Fibrin gel was prepared by 2.5 mg/ml fibrinogen (EMD, cat #341578) and 0.5 U/ml thrombin (Sigma, cat #T-9326). A 10 μL fibrin gel/cell solution was spotted in the middle of 24-well plate and incubated for 10 mins at 37° C. for solidification. E7V medium was then applied. Immunostaining was performed on day 4 and the structures were imaged using confocal microscopy.

Oxygen-Induced Retinopathy Model: The experiments were performed under approval from UW-Madison Ophthalmology and Visual Science IRB. Oxygen-induced retinopathy was induced in C57/BL6 wild-type mice as previously described²¹. Briefly, postnatal day seven mice were exposed in 75% oxygen for five days. At day postnatal day 12, they were transfer back to room air and received 1 μl intravitreal injection containing 5×10⁴ cells. Phosphate buffered saline (PBS) was used as vehicle and injected as the control. Five days later, retinas were harvested and immunostaining was performed.

Hind Limb Ischemia Model: The experiments were performed under approval from UW-Madison Cardiovascular Physiology Core Facility IRB. The Hind limb ischemia model was generated as previously described²². Briefly, 10⁻¹² weeks old female athymic nude mice (Crl:NU(NCr)-Foxn1^(nu), Charles River Laboratroies, Chicago, Illinois) were used. Ten to twenty weeks old instead of four to six weeks old mice were used as the recovery of the older mice was slower and more similar to human limb ischemia. The common iliac artery was ligated in the abdominal cavity and just caudal to the inguinal ligament, the femoral artery was ligated in two locations and removed. The mice were randomly assigned into four groups right after surgery and injected cells or DF12 medium. The cells (0.3×10⁶, 1×10⁶, or 3×10⁶ cells per mouse) were suspended in 300 μl DF12 medium and injected intramuscularly into six site of the gracilis muscle in the ischemic leg. The surgery was performed on seven to eight mice per day.

Nitric Oxide Production Assay: The endothelial cells were seeded on vitronectin coated 24-well plate (1×10⁵ cells/well). AECs were cultured in FVIR+Ins medium. HUVEC (Lonza, cat #CC-2519) was cultured in EGM2 (Lonza, cat #CC-3202)) medium. HCAEC (Lonza, cat #CC-2585) was cultured in EGM2 medium for one day and then in FVIR+Ins medium for another day. Two days later, all the medium were changed to fresh FVIR+Ins medium containing 1 μM DAF-FM (Life technologies, cat #D-23844). Cells were cultured for 30 mins and then harvested for flow cytometric analysis. DAF-FM is nonfluorescent until it reacts with NO to form a fluorescent benzotriazole. To achieve the consistent results, the same cell density and same medium is used after adding DAF-FM.

Oxygen Consumption Assay: 4×10⁴ cells/well were seeded on the XF24-well plate (Seahorse Bioscience) for overnight. AECs were cultured in FVIR medium, HCAEC and HUVEC were culture in EGM2 medium. One day later, medium was changed to Mito Assay medium (Seahorse Bioscience) and oxygen consumption rate was measured by XF24 analyzers according to manufacture's instruction (Seahorse Bioscience). Oligomycin (0.5 μM) was injected at time point 3 to abolish the oxygen consumption by inhibiting ATP-synthase. FCCP (2 Mitochondrial uncoupler) was injected at time point 6 to uncouple the electron transport chain from the oxidative phosphorylation thus measuring the maximal respiration capacity. To measure non-mitochondrial respiration, 1 μm Antimycin A and 1 μm Rotenone were applied simultaneously at time point 9 to completely block the electron transport chain at cytochrome bc1 (complex III) and NADH dehydrogenase (complex I), respectively.

Shear Stress Response: Shear stress response was assayed using an ibidi Pump System (Red perfusion set, μ-Slide VI 0.4). For each channel of μ-Slides, 30 μl cell suspension (5×10⁵ cells/ml, with 1011M Y27632) was loaded. After cell attached, 130 μl fresh medium was added to each channel. Two days later, μ-Slide was perfused by ibidi Pump System. After perfusion for 24 hours, cells were harvested and immunostained.

Since FVIR+Ins medium promoted the elongation of endothelial cells, E7V medium was used to culture “five factors” AECs before and during the 24-hour shear stress response experiment.

Leukocyte Adhesion Assay: All endothelial cells were cultured on a fibronectin coated 24-well plate. AECs were cultured in FVIR medium; HUVEC and HCAEC were cultured in EGM-2 medium (Lonza). When the cells reached to 100% confluence, they were treated with or without 10 ng/ml TNFα for four hours. Then 1×10⁶ U937 cells were suspended in 0.5 ml fresh RMPI1640+10% FBS and added to each well. Twenty to 60 minutes later, cold medium (RMPI1640+10% FBS) was used to gently wash away the non-attached cells. Washing was repeated two more times. Cells were imaged immediately.

Antibody Reagents: Anti-mouse CD41-FITC (Biolegend, Catalog #133904), Anti-mouse CD45-FITC (STEMCELL technologies, Catalog #10710), Anti-mouse CD144-PE (BD, Catalog #562243), Anti-mouse CD31-APC (BD, Catalog #551262), Anti-human CD31-FITC (BD, Catalog #555445), Anti-human CD31-V421 (BD, Catalog #564089), Anti-human CD31-PE (BD, Catalog #555446), Anti-human CD34-647 (BD, Catalog #555824), Anti-human CD144-647 (BD, Catalog #561567), Anti-human DLL4-APC (Miltenyi, Catalog #130-096-560), Anti-human CXCR4-APC (BD, Catalog #560936), Anti-CD34 Micro bead (Miltenyi, 130-046-703), Anti-CD144 Micro bead (Miltenyi, 130-097-857), Anti-pAKT (ser473) (Cell signaling, Catalog #4060), Anti-AKT (Cell signaling, Catalog #4691), Anti-GAPDH (EMD Millipore, Catalog #MAB374).

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The invention has been described in connection with what are presently considered to be the most practical and preferred embodiments. However, the present invention has been presented by way of illustration and is not intended to be limited to the disclosed embodiments. Accordingly, those skilled in the art will realize that the invention is intended to encompass all modifications and alternative arrangements within the spirit and scope of the invention as set forth in the appended claims.

TABLE 4 Genes Enriched in P1 (arterial endothelial cells) vs. P3 (venous cells) Average Average SYMBOL Venous arterial Arterial/Venous p EFNB2 3.385 132.8169231 39.2369049 9.19431E−05 ZFP91 3.728333333 40.26538462 10.79983494 0.000240266 ABI1 10.46833333 103.5061538 9.887548529 0.000275893 RB1CC1 1.223333333 26.68538462 21.8136659 0.000475352 PAM16 1.233333333 109.8853846 89.0962578 0.000478996 NDUFB2 68.985 204.7292308 2.967735461 0.000997087 ECE2 32.285 241.0869231 7.467459287 0.001219051 GLOD4 29.72 115.0207692 3.870147013 0.001231445 ATP6V1H 9.261666667 96.89230769 10.4616492 0.001476268 UQCR11 400.9133333 867.3530769 2.163442831 0.001500257 BCR 0.273333333 17.03230769 62.31332083 0.001570238 KLF7 6.853333333 59.80615385 8.726578869 0.001641459 YES1 5.766666667 44.61384615 7.736505113 0.001805012 GPX4 195.8316667 519.4053846 2.652305388 0.001808462 CRAMP1L 2.33 12.18153846 5.228128095 0.001919003 PDLIM7 22.71166667 104.6307692 4.606917263 0.002007834 SUV420H2 0.21 42.26923077 201.2820513 0.002058135 CLTA 9.336666667 93.24230769 9.986680581 0.0021114 SIK3 0.288333333 9.756923077 33.83903957 0.002112886 APOOL 28.395 227.7223077 8.019803053 0.002179598 2410004B18RIK 0.103333333 16.97615385 164.2853598 0.002200093 PMPCA 5.285 89.88615385 17.00778692 0.002332837 SLC20A1 13.90833333 141.1692308 10.14997465 0.002452212 CRYZ 3.031666667 81.01 26.72127543 0.002540742 STIP1 93.86166667 275.8192308 2.93857163 0.002676347 2310033P09RIK 1.333333333 40.97461538 30.73096154 0.002701952 SNRPN 1.75 34.89384615 19.93934066 0.002947216 SNURF 1.75 34.89384615 19.93934066 0.002947216 PKIG 27.89166667 135.9292308 4.873471076 0.002989368 ZFP69 1.728333333 74.69538462 43.21815889 0.003117547 ZEB1 19.37 42.88769231 2.214129701 0.003365306 NFKB1 4.178333333 28.84 6.902273634 0.003383717 UBQLNI 8.751666667 82.31230769 9.405329388 0.003450139 SCP2 40.35 131.2307692 3.252311505 0.003458867 NFAT5 1.718333333 12.03384615 7.003208237 0.00356317 GALNT7 2.171666667 24.92846154 11.47895389 0.003740709 SLC11A1 6.113333333 15.63692308 2.557839107 0.003873468 MAPK7 4.216666667 32.58384615 7.727394345 0.00388953 DNAJA2 43.11333333 155.7569231 3.612732095 0.004169191 3200002M19RIK 31.69166667 128.7215385 4.061684096 0.004182439 MYCT1 19.67166667 109.9984615 5.591720488 0.004228163 UNC5B 0.413333333 53.98923077 130.6191067 0.004302974 NOTCH1 6.468333333 25.01153846 3.86676709 0.004390574 VCP 87.10333333 236.8469231 2.719148786 0.004391778 MTX2 3.993333333 42.71384615 10.69628869 0.004393955 MYO6 4.123333333 22.79769231 5.528947205 0.004450296 EIF1A 51.38666667 182.0284615 3.54232865 0.004523565 SFT2D1 29.595 145.1507692 4.904570679 0.004672191 HNRPDL 89.60333333 201.6476923 2.250448558 0.004872772 OS9 0.843333333 18.93846154 22.45667376 0.005041053 OSBPL11 1.883333333 67.16923077 35.66507828 0.005042374 TMEM2 46.21 126.8084615 2.744177917 0.005122916 NCLN 5.511666667 53.11923077 9.637598567 0.00512415 CCNH 26.70166667 91.59307692 3.430238197 0.005293571 PODXL 2.241666667 22.92230769 10.22556477 0.005298181 CPSF2 11.525 69.92 6.06681128 0.005372826 RERE 2.495 10.02230769 4.016956991 0.005444336 EIF4E2 63.23833333 151.6823077 2.398581678 0.005508351 CSGALNACT1 1.436666667 27.72384615 19.29734071 0.005582996 STAG2 16.92666667 99.05769231 5.852167722 0.005604699 CATSPER2 0 4.33 #DIV/0! 0.005764138 ORC4 29.08833333 125.2469231 4.305744219 0.005852601 FNTA 11.80333333 66.92307692 5.669845546 0.006003204 MDM2 2.74 52.58384615 19.19118473 0.006038551 AAAS 4.686666667 83.18307692 17.74887843 0.006204517 CCNG2 6.808333333 77.16 11.33317013 0.006289792 XPNPEP1 42.52166667 156.0361538 3.669568154 0.006315041 ABCA1 1.843333333 31.11153846 16.87786897 0.006324339 CENPB 3.355 24.35076923 7.258053422 0.006437385 ATP6V1B2 15.295 154.7784615 10.11954636 0.006463226 1810011O10RIK 13.18333333 116.0692308 8.804240008 0.00664935 PALM 9.896666667 56.17153846 5.675803819 0.006659886 1110057K04RIK 15.285 106.5630769 6.97174203 0.006710143 TMED10 86.775 189.76 2.186804955 0.007271129 RELL1 6.05 54.70769231 9.04259377 0.007359743 MICALL1 0.476666667 10.91461538 22.89779451 0.007489279 CYFIP1 37.99833333 86.40923077 2.274026864 0.007616271 GMFG 1.781666667 45.36538462 25.46233 0.007680945 MMGT1 11.83833333 57.67461538 4.87185263 0.007898165 MRPL19 3.635 29.56461538 8.133319225 0.007954454 ZFP770 0.115 12.44153846 108.187291 0.008008639 HEY1 1.525 49.74769231 32.62143758 0.008135942 AI462493 19.63166667 68.19 3.473469734 0.008317939 MAP3K3 4.02 48.54923077 12.07692308 0.008461151 ARL8A 4.375 16.96153846 3.876923077 0.009161649 PTPRG 2.28 19.35153846 8.487516869 0.009360361 KIF1C 0.446666667 3.813076923 8.53673938 0.00945174 SLC16A13 0.035 32.42461538 926.4175824 0.009459486 TANC1 1.568333333 17.25153846 10.99991825 0.009468885 CARKD 0.571666667 65.80307692 115.1074232 0.009662523 IRF2 5.738333333 28.24538462 4.922227932 0.009848846 TMEM126A 51.09333333 159.66 3.12486952 0.010061198 SLC9A3R2 2.42 60.53769231 25.01557533 0.010070149 RBM17 11.22833333 109.3530769 9.739030155 0.010121604 NDFIP2 5.515 61.11384615 11.08138643 0.01026201 WDR37 6.125 60.00307692 9.796420722 0.010282102 ANKRD13A 0.711666667 22.15615385 31.13276887 0.010510297 CAMK2N1 0.038333333 10.04 261.9130435 0.010661901 CYBA 61.34333333 211.6038462 3.449500291 0.010705172 9430020K01RIK 6.446666667 33.73153846 5.232399968 0.010782094 PON3 47.42166667 235.8323077 4.973091928 0.010947494 ZIK1 1.445 32.63846154 22.58717061 0.011011179 TAF6 6.866666667 143.5169231 20.90052278 0.011094949 ARPC1B 15.71333333 118.2546154 7.525749812 0.011196008 HERPUD1 0.075 80.46692308 1072.892308 0.011239847 ZC3H7A 19.84833333 94.36769231 4.754439112 0.011339573 USP34 16.32166667 40.75307692 2.496869821 0.01139032 VPS41 51.05166667 151.2569231 2.962820471 0.011548761 PTRF 100.8383333 262.8869231 2.607013765 0.011974959 SPARCLI 26.95166667 141.1661538 5.237752292 0.012197776 ATPAF1 0 8.841538462 #DIV/0! 0.012432885 RTF1 7.266666667 19.70769231 2.712067749 0.012510393 TRAF3IP2 0.021666667 10.25307692 473.2189349 0.012650349 MPV17L 62.90166667 133.8876923 2.128523764 0.012821527 METTL1 0.608333333 21.49538462 35.33487882 0.012864088 AP2A2 30.55333333 66.98615385 2.192433576 0.012937774 BC052040 0.421666667 35.65923077 84.5673457 0.012992012 OTUD6B 1.256666667 134.4076923 106.9557233 0.013133609 RBM27 6.238333333 20.85692308 3.34334861 0.013572071 STOX2 4.311666667 16.90692308 3.921203651 0.013704227 DUSP1 22.30833333 115.6538462 5.184333784 0.013959937 APRT 143.845 392.3446154 2.727551291 0.013992332 KLF11 1.945 13.22615385 6.800079098 0.014138226 MBNL1 54.94166667 162.4823077 2.957360371 0.014235892 NDUFB6 176.9133333 435.2423077 2.460200707 0.01426922 HS6ST1 0.331666667 18.20692308 54.89524546 0.014290794 RNF103 0.058333333 3.42 58.62857143 0.014436475 GPR108 0 34.85230769 #DIV/0! 0.014485379 CABLES2 0.03 40.96384615 1365.461538 0.014513813 1110012L19RIK 0.075 51.40076923 685.3435897 0.014638158 FAM102B 6.878333333 48.90153846 7.109504017 0.015105008 GIT2 31.37 66.93461538 2.13371423 0.015337561 SH2D3C 11.65166667 63.51 5.450722357 0.015462751 NDUFAF4 6.903333333 27.92923077 4.045760131 0.015588477 TACC1 23.90333333 66.06692308 2.763920921 0.015677661 TMEM107 0 54.48615385 #DIV/0! 0.016146777 MAP3K11 0.808333333 21.93384615 27.13465504 0.016217106 HDHD2 12.73833333 69.06307692 5.421672923 0.016455021 ST3GAL5 2.035 27.55615385 13.54110754 0.016545693 TFDP2 1.631666667 8.296923077 5.084937534 0.017053524 FAM70A 72.96666667 231.5038462 3.172734301 0.017064899 ATP6VIC1 21.12333333 70.67461538 3.345807893 0.017762152 ARL4C 0 10.77384615 #DIV/0! 0.017765223 WDR1 118.985 361.9530769 3.042005941 0.017812468 SPPL3 24.87666667 90.63538462 3.643389439 0.018003641 GM10406 29.53833333 83.45769231 2.825402888 0.018369717 RNASEK 36.47 153.1953846 4.200586362 0.01843833 SATI 207.5716667 736.1584615 3.546526717 0.018518169 NGFRAP1 163.3833333 366.7930769 2.244984659 0.018834065 SCNM1 5.593333333 59.61384615 10.65801779 0.01890972 TMEM135 0.041666667 40.40076923 969.6184615 0.018917381 THBD 4.881666667 38.83615385 7.955511201 0.018990321 PIGC 4.391666667 45.81769231 10.43287111 0.01906959 FAM108B 2.291666667 30.18769231 13.17281119 0.019131469 GTF2A1 152.4783333 318.5053846 2.088856677 0.019181905 KLF3 16.465 83.83461538 5.091686328 0.019245785 CELSRI 0.176666667 9.797692308 55.4586357 0.019332519 BAG1 6.505 38.77692308 5.961095016 0.019352643 OMA1 0.8 71.75 89.6875 0.019386958 WTAP 53.74333333 133.7023077 2.487793358 0.019456377 SRPRB 13.555 97.11846154 7.164770309 0.019611167 GOT1 3.796666667 55.56615385 14.63551023 0.019997176 UBE2J1 8.225 31.62076923 3.844470423 0.020059233 LNPEP 0.87 4.605384615 5.293545535 0.020273547 CLK2 7.611666667 49.52307692 6.506206734 0.020375008 PSG25 0.573333333 1.700769231 2.966457961 0.020531763 PLK2 269.0066667 586.1761538 2.179039505 0.02053319 GNGT1 0.228333333 2.098461538 9.190342504 0.020576308 BC004004 1.505 63.48615385 42.18349093 0.020608049 PRSS23 0.18 38.21153846 212.2863248 0.020670808 TMEM179B 0.498333333 48.33923077 97.00180087 0.020676696 POFUT2 8.811666667 76.23692308 8.651816502 0.020698889 PDCD7 0.131666667 34.84153846 264.6192795 0.020842697 MYO10 24.63833333 75.11153846 3.048564099 0.021072143 ZFP830 3.733333333 13.74615385 3.682005495 0.02125756 CUL1 53.66166667 151.5253846 2.823717451 0.021439414 PHLPP2 0.356666667 2.52 7.065420561 0.021609083 TCF4 65.40666667 136.8769231 2.092705989 0.021644076 FAM82B 0.046666667 6.852307692 146.8351648 0.021781048 MTHFS 1.378333333 40.47230769 29.36322203 0.021829631 SEC11C 18.31 100.5761538 5.492963072 0.021830525 CYP20A1 2.475 63.35307692 25.5972028 0.021853266 GJA4 0 341.8130769 #DIV/0! 0.021930681 MRPS17 53.04333333 152.1369231 2.868162944 0.021976091 TCN2 0.865 63.31461538 73.19608715 0.022099139 ERICH1 7.178333333 26.62923077 3.709667625 0.022136522 CUL4A 8.706666667 89.80307692 10.31428908 0.022308948 GALT 9.176666667 85.35846154 9.301684875 0.022314096 SLC41A1 0.126666667 11.60615385 91.62753036 0.022449628 PPP2R3C 1.751666667 35.29384615 20.14872283 0.022578109 RFTN2 2.033333333 37.20307692 18.29659521 0.022607793 TNS1 0.323333333 19.85461538 61.40602696 0.022707466 N4BP1 3.005 22.25307692 7.405350058 0.022840249 AP1B1 7.47 45.62461538 6.107712903 0.022906176 PHB 107.2916667 246.0061538 2.29287289 0.022956614 UBAC1 2.656666667 13.19846154 4.968053277 0.023037392 RAB5C 5.825 17.75153846 3.047474414 0.023133369 DARS2 1.083333333 40.68538462 37.55573964 0.023179456 FZD4 3.078333333 42.66692308 13.86039732 0.023271942 REEP5 15.91833333 56.58 3.55439221 0.023371665 ARF6 14.16666667 35.28230769 2.490515837 0.023533819 NMD3 61.78833333 170.4692308 2.758922625 0.023562786 MKNK2 16.75666667 66.63230769 3.976465548 0.023626939 0910001L09RIK 0.408333333 26.54769231 65.01475667 0.023758909 TPP1 12.98 59.35846154 4.573070997 0.02376108 3110056O03RIK 0.93 18.67692308 20.08271299 0.023780867 ADAM15 3.48 19.44692308 5.588196286 0.023832747 ANGPT2 0 3.886923077 #DIV/0! 0.023913439 TRMT2B 0.348333333 18.88384615 54.21199853 0.024410915 XPR1 2.316666667 18.66692308 8.057664638 0.0245685 LAMA4 38.52 123.1223077 3.196321591 0.024670168 RBM15B 1.35 10.13230769 7.505413105 0.024726345 PLAG1 2.741666667 14.81923077 5.405190554 0.024945921 1110001J03RIK 42.435 114.24 2.692117356 0.025236719 DNAJC21 1.855 32.87076923 17.72009123 0.025455253 ANKRD37 0 19.33384615 #DIV/0! 0.025456764 HEBP1 0.083333333 2.872307692 34.46769231 0.025492603 EBF1 9.5 74.50538462 7.842672065 0.02550248 TOMM70A 25.685 96.77769231 3.767868106 0.025592427 NFRKB 0.12 8.373846154 69.78205128 0.025651677 RNF34 6.471666667 75.87769231 11.72459835 0.025710175 TMEM161A 0 6.103076923 #DIV/0! 0.025750694 FDXR 0 5.233076923 #DIV/0! 0.025890656 HEXA 25.26166667 115.6738462 4.5790267 0.025964577 RHOG 8.52 69.45615385 8.152130733 0.02611705 MAPKAPK2 0.276666667 19.44153846 70.27062095 0.026290641 A430005L14RIK 14.65666667 116.7207692 7.963664037 0.026423167 ECHDC1 3.351666667 50.15307692 14.96362315 0.026501523 TRAF7 27.59833333 92.11923077 3.33785485 0.026596211 CXCR4 0 22.95230769 #DIV/0! 0.026654915 ZFP169 0.053333333 1.375384615 25.78846154 0.026750673 FERMT2 35.28 100.5438462 2.849882261 0.026789286 MYLK4 0.515 1.243846154 2.41523525 0.026929464 FAM172A 5.861666667 44.64769231 7.616893769 0.027185609 NIT2 22.61 127.0746154 5.620283741 0.027205719 GOLGA2 0.39 8.923846154 22.8816568 0.027392671 ATP6V1E1 46.32166667 168.2253846 3.631678148 0.027790291 2310016C08RIK 6.558333333 79.30769231 12.09265956 0.028063943 LRRC47 0.076666667 18.86461538 246.0602007 0.028071959 VPS13B 0.915 11.73615385 12.82639765 0.028077765 RFESD 1.87 34.06076923 18.2143151 0.028109316 STRBP 9.725 27.59923077 2.837967174 0.028230906 NDRG3 0.303333333 29.64692308 97.73710904 0.028272119 SFT2D2 0.026666667 15.18615385 569.4807692 0.028377348 WSB1 248.3766667 560.1653846 2.255305992 0.028735922 MRE11A 0.725 49.67230769 68.51352785 0.028793407 IFNGR2 15.70166667 59.68307692 3.801066357 0.028817418 1700123O20RIK 39.35666667 94.47 2.400355721 0.02904505 MKI67IP 17.88 83.63692308 4.677680262 0.029243856 SIRT2 10.35166667 67.20692308 6.492377048 0.029404512 2510012J08RIK 0.23 7.200769231 31.30769231 0.029411528 TMEM188 2.975 37.80923077 12.70898513 0.02958981 USP28 0.366666667 27.24538462 74.30559441 0.029612383 HRSP12 7.301666667 74.51769231 10.20557302 0.029670977 FCER2A 0.435 1.655384615 3.805481874 0.029723822 INPP5K 0.178333333 49.50230769 277.5830338 0.029804456 TMEM134 5.673333333 23.44769231 4.132965742 0.029850332 HSDL1 2.213333333 117.4130769 53.04807692 0.029853034 TRIM24 14.90666667 51.56692308 3.459319527 0.029874672 1600012H06RIK 1.013333333 30.41153846 30.01138664 0.02993989 MIER2 0.113333333 25.69153846 226.6900452 0.029975659 EPN2 0.393333333 67.31153846 171.13103 0.030066295 CKB 6.455 74.98307692 11.61627838 0.030084135 ATG5 36.51666667 108.35 2.967138293 0.030330758 BIN3 1.095 72.92230769 66.59571479 0.030339038 SIRT6 11.55166667 30.65 2.653296783 0.030360402 PFKL 6.498333333 72.58615385 11.16996469 0.030418381 CXXC5 11.08666667 51.99923077 4.690249318 0.030572682 2700078K21RIK 0.695 95.28307692 137.0979524 0.030787086 SNIP1 0.418333333 7.924615385 18.94330371 0.030894971 EXOC6 3.431666667 56.72615385 16.5302051 0.030922331 ANGEL2 16.89833333 54.69846154 3.23691458 0.03096661 PPP5C 5.806666667 44.66153846 7.691424534 0.031218815 ECE1 111.9 274.79 2.45567471 0.031225536 STARD3NL 19.37333333 86.21307692 4.450089999 0.031238384 HPCAL1 10.92833333 67.22692308 6.15161718 0.031429075 NDUFS2 73.09333333 241.6146154 3.305562961 0.031732727 BCL6B 43.01166667 120.15 2.79342814 0.031754776 AP3S1 12.56166667 55.00769231 4.379012257 0.031755004 PPPDE2 0.086666667 23.73307692 273.8431953 0.031827411 TRIB1 3.995 18.30384615 4.581688649 0.031860429 AP3S2 6.46 20.70307692 3.204810669 0.031865004 TRIM35 14.28 62.37307692 4.36786253 0.031931969 UBE2M 0.461666667 8.538461538 18.49486254 0.03200187 GADD45GIP1 1.156666667 7.919230769 6.846597207 0.032007181 GM7244 0.346666667 2.086153846 6.017751479 0.032191261 DTL 14.22166667 76.84615385 5.403456265 0.032255499 GSTM1 0 90.04923077 #DIV/0! 0.032400938 SSH1 0.678333333 4.932307692 7.271215271 0.032554474 CARS 3.118333333 40.93 13.12560128 0.032685951 GM6654 20.50833333 75.04 3.659000406 0.032959343 RBM41 5.021666667 20.57846154 4.097934591 0.033106439 HSPA4L 0.036666667 5.396153846 147.1678322 0.033300757 VPS28 103.3033333 249.6053846 2.416237468 0.033470154 RFK 8.44 54.41615385 6.447411593 0.03351173 MCCC2 0.193333333 48.14153846 249.0079576 0.033669052 TADA2B 0.238333333 5.889230769 24.71005917 0.033685451 NDOR1 1.638333333 16.99769231 10.37499022 0.033873322 USP3 26.95333333 75.01538462 2.783157975 0.033890802 MAN1C1 3.095 29.26 9.453957997 0.033934677 ANKRD54 0.041666667 30.51307692 732.3138462 0.034039372 TTLL12 1.216666667 25.01769231 20.56248683 0.034336372 VAC14 0.415 5.976153846 14.40037071 0.034356148 CLPTM1 2.968333333 16.86 5.679955081 0.03444528 1110020G09RIK 4.076666667 54.71692308 13.42197622 0.034502276 MLH3 0.658333333 8.206153846 12.46504382 0.034602385 SCYL2 0.018333333 1.806923077 98.55944056 0.034995114 MECOM 6.53 97.88538462 14.99010484 0.035000679 LPCAT3 5.005 48.18384615 9.627142089 0.035029409 ZFP457 0.336666667 2.023846154 6.011424219 0.035086209 ZFP637 44.54 132.8969231 2.983765673 0.035138186 CEP250 0.098333333 5.122307692 52.09126467 0.035266592 CAMK2G 2.091666667 36.67538462 17.53404842 0.035309188 GRPEL2 1.341666667 15.22538462 11.34811276 0.035436744 PKMYT1 1.156666667 35.49615385 30.68831745 0.035543986 IFT46 38.585 94.58153846 2.451251483 0.035658758 DPM3 45.605 99.79230769 2.188187867 0.035678768 RASSF2 2.685 16.88923077 6.290216301 0.035699489 PXK 1.29 19.44692308 15.07513417 0.035717616 FOXP2 1.498333333 25.56769231 17.0640883 0.035990592 SLC25A1 3.498333333 48.71846154 13.92619196 0.03616713 2610002I17RIK 9.57 57.04923077 5.961257134 0.036249471 SLC38A7 0 2.803076923 #DIV/0! 0.03650076 NCSTN 19.76333333 70.50384615 3.567406619 0.036654248 1810048J11RIK 0 25.67769231 #DIV/0! 0.036656075 RPP40 7.81 40.37846154 5.170097508 0.036738428 SMTN 10.585 37.49692308 3.542458486 0.036844152 MTHFD2 2.961666667 67.39230769 22.7548591 0.036927106 CSAD 2.518333333 22.9 9.093315685 0.03721687 PLCB4 0.061666667 20.81769231 337.5841996 0.037255767 MAP3K7 8.493333333 41.92692308 4.936450912 0.037295572 DNAJC17 0.176666667 31.84461538 180.2525399 0.037395996 5430437P03RIK 16.90333333 45.21384615 2.674847929 0.037578453 CCND2 71.25 177.8453846 2.496075574 0.037648986 DPM2 37.36666667 129.3623077 3.461970768 0.037677582 2310036O22RIK 19.51333333 51.35307692 2.631691677 0.037728855 KLHL21 0.893333333 20.34384615 22.77296211 0.038085178 FAM165B 61.485 142.6907692 2.320741144 0.038115442 FKBP14 0.071666667 54.78 764.372093 0.038340315 ARHGAP5 17.34333333 71.04461538 4.096364523 0.038370987 2310008H04RIK 2.466666667 20.33923077 8.245634096 0.038383648 ZFP592 0.285 20.45615385 71.77597841 0.038495223 TMTC4 5.511666667 31.10307692 5.64313461 0.038498387 HIGD1A 3.58 19.04153846 5.318865492 0.038573935 SMPDL3B 0 8.326923077 #DIV/0! 0.038797907 RCC2 22.76666667 50.06769231 2.199166573 0.039044589 KBTBD2 8.396666667 77.70538462 9.254313372 0.039141354 TERF1 2.76 27.59230769 9.997212932 0.039151289 ACER2 0.85 10.87153846 12.79004525 0.039158693 MGLL 0.093333333 25.18307692 269.8186813 0.03921294 SRGAP1 3.741666667 13.83384615 3.697241734 0.039355605 APPL2 1.191666667 31.36461538 26.31995697 0.039489916 LNX1 0 1.966153846 #DIV/0! 0.039521684 MIPOL1 0.363333333 17.92 49.32110092 0.039567716 SLC23A2 7.303333333 29.13538462 3.989326967 0.039581995 PAIP2 219.0333333 454.2284615 2.073786919 0.039729082 CERK 3.871666667 21.01307692 5.427398258 0.039748408 LAGE3 30.33833333 133.3246154 4.394592607 0.039911992 NOP14 5.015 56.62 11.29012961 0.040136837 GMPPB 11.83333333 66.38692308 5.610162514 0.040183033 PRR5L 22.68833333 63.24384615 2.787505156 0.040241287 ZCWPW1 0.04 27.26846154 681.7115385 0.040286692 2510006D16RIK 123.25 263.7661538 2.140090498 0.04028986 PPM1E 0 5.566153846 #DIV/0! 0.040391847 PCYT1A 2.993333333 15.98076923 5.338787048 0.04052893 1110034B05RIK 12 84.33230769 7.027692308 0.04072132 PGAP2 0 50.55923077 #DIV/0! 0.040730276 SRGN 0.238333333 33.19846154 139.2942442 0.040969616 LPCAT1 1.751666667 12.03461538 6.870379858 0.041139103 LYL1 0.573333333 11.66307692 20.34257603 0.041144687 GM14430 0.275 8.703846154 31.65034965 0.041267689 GM14434 0.275 8.703846154 31.65034965 0.041267689 AGGF1 4.063333333 55.85384615 13.7458194 0.041344615 GTL3 77.075 248.4761538 3.22382295 0.041361201 KCNQ1 0.031666667 1.834615385 57.93522267 0.04147258 ANXA11 0.123333333 1.683846154 13.65280665 0.041566921 GIMAP1 15.75666667 50.43076923 3.200598851 0.041692451 DNAJB9 0 28.25307692 #DIV/0! 0.041693969 COX18 2.021666667 16.60461538 8.213329951 0.04188168 PRODH 0 31.34384615 #DIV/0! 0.041905819 GM5113 9.601666667 22.49923077 2.343263055 0.041978051 HINT2 11.93166667 55.91615385 4.686365737 0.042079062 LYPLA2 2.881666667 35.32923077 12.25999911 0.042084923 MAP3K2 0.046666667 2.787692308 59.73626374 0.042146552 GALE 23.73666667 96.33307692 4.058407959 0.042260317 PLAT 0.16 19.67230769 122.9519231 0.042532177 ZFP358 1.115 21.94 19.67713004 0.042682574 ZCCHC3 16.50166667 44.49923077 2.696650688 0.042818734 PPP2R4 6.496666667 21.63307692 3.329873308 0.043018399 AKR1B3 103.7033333 277.6669231 2.677512035 0.043535478 GM10345 0 32.37153846 #DIV/0! 0.043551944 ZHX1 0.88 22.74615385 25.8479021 0.043595271 RAPGEF5 3.076666667 17.74384615 5.767230603 0.043739677 2310003L22RIK 0 20.38615385 #DIV/0! 0.043829833 FBRSL1 0.531666667 5.803076923 10.91487823 0.044093031 TMOD1 12.35166667 38.17461538 3.090644883 0.044263895 TBC1D23 2.17 21.87384615 10.08011343 0.044386935 ELAC2 0.556666667 57.29923077 102.9327499 0.044398266 SPINT2 0 25.24769231 #DIV/0! 0.04442694 API5 67.80333333 162.0369231 2.389807626 0.044541725 SKIL 62.55166667 144.3038462 2.306954456 0.044578008 ASS1 2.425 50.87076923 20.9776368 0.044658449 ZFP809 0.548333333 6.85 12.49240122 0.044775293 PECAM1 87.48666667 216.1353846 2.470495138 0.044778294 LCLAT1 0.03 12.22153846 407.3846154 0.044791712 LIN7C 34.86666667 92.33692308 2.648286513 0.044837935 DAZAP1 3.816666667 16.06538462 4.209271078 0.044855774 BMP1 12.96666667 59.58846154 4.595511173 0.044873594 ALAS2 0.033333333 12.3 369 0.045035951 ARFGEF2 0.013333333 12.11538462 908.6538462 0.045037558 KHNYN 0 2.626923077 #DIV/0! 0.045084098 ECM1 0 27.87153846 #DIV/0! 0.045122243 MTSS1L 0.92 8.325384615 9.049331104 0.045141405 RIC8B 1.546666667 17.55923077 11.35295093 0.045459795 FAM100A 0.071666667 7.908461538 110.3506261 0.045489009 POP7 27.48833333 108.7146154 3.954936593 0.045527616 TMEM8B 0.453333333 14.72538462 32.48246606 0.04554072 HECTD1 18.975 49.41769231 2.604357961 0.04578972 PIH1D1 7.455 49.70076923 6.66676985 0.045985496 GNE 0.055 2.502307692 45.4965035 0.046063511 LYSMD3 0.82 42.79846154 52.19324578 0.046070404 1110003E01RIK 0.468333333 34.33153846 73.30577607 0.046077666 FUT10 0.02 5.203846154 260.1923077 0.046298882 PEX11B 4.003333333 39.44923077 9.854095946 0.046489188 RNF31 0.471666667 24.92153846 52.83718402 0.046492936 OGFR 0.033333333 14.2 426 0.046557415 GCFC1 30.21166667 75.21 2.489435648 0.04657836 WDR55 7.323333333 60.16923077 8.216098876 0.046768358 FAM117A 0 3.892307692 #DIV/0! 0.046981029 EIF2B5 14.40833333 66.86153846 4.640476932 0.047035175 PPFIBP2 0.528333333 13.06461538 24.72797865 0.047178928 TMEM109 9.633333333 56.26846154 5.841016769 0.047417695 MMP15 8.233333333 24.76538462 3.007941451 0.047597294 TRMT11 7.843333333 31.60692308 4.029781948 0.048005041 ALAS1 14.72 49.46384615 3.360315635 0.048187395 CCPG1 0.54 22.89076923 42.39031339 0.048240471 GAK 5.171666667 28.74461538 5.558095144 0.048289197 RANBP6 1.16 8.937692308 7.704907162 0.048307814 HOXB4 0.055 4.497692308 81.77622378 0.048345333 SLC20A2 1.611666667 39.54384615 24.53599555 0.048465284 MRPS5 18.02833333 51.36846154 2.849318381 0.048528808 TTI1 0 8.923076923 #DIV/0! 0.048560674 GRIA2 0 33.54692308 #DIV/0! 0.049032855 ABCB7 3.866666667 17.84153846 4.614190981 0.049129942 SLC18A2 3.061666667 55.74 18.20577028 0.049196079 SARS2 0.663333333 38.67 58.29648241 0.04921158 ALKBH3 2.72 32.07076923 11.79072398 0.049504769 HES6 0 35.96923077 #DIV/0! 0.049589735 MTMR9 0.065 28.03076923 431.2426036 0.049786268 IRF2BP1 0 2.435384615 #DIV/0! 0.049878388 VPS26B 2.686666667 12.53692308 4.66634854 0.050007937 CEP68 2.906666667 38.03923077 13.08689132 0.050119545 ANKIB1 2.796666667 19.03769231 6.807279729 0.050190369 UBA7 0.365 8.059230769 22.0800843 0.05025586 PDZD8 12.44333333 29.49 2.369943745 0.050457696 RNF14 15.77 60.10538462 3.811375055 0.050490229 PTMS 7.316666667 38.12538462 5.210758717 0.050512605 ARMC5 2.638333333 18.70230769 7.088682638 0.050531575 TET1 0.811666667 12.63384615 15.56531354 0.050672764 FZD10 0.533333333 3.283846154 6.157211538 0.050692702 SAMM50 8.068333333 42.92461538 5.320134111 0.050866203 TFAM 15.87 42.34923077 2.668508555 0.050951714 GPATCH2 1.16 19.14153846 16.50132626 0.051154694 REPIN1 2.006666667 14.55461538 7.25313059 0.051272867 2010012O05RIK 6.165 19.39153846 3.145423919 0.051402534 FAM78B 0.043333333 5.774615385 133.260355 0.051446212 TMEM165 8.953333333 40.03846154 4.471905607 0.05145031 NTS 0 85.65692308 #DIV/0! 0.051571632 ST7L 3.53 21.37230769 6.0544781 0.051624534 AMN1 0.195 21.10384615 108.2248521 0.051674438 NSUN6 0 1.520769231 #DIV/0! 0.051720659 ARFGAP1 3.646666667 45.61846154 12.50963296 0.052127566 SLC4A7 9.286666667 32.87307692 3.539814457 0.052423429 PELI2 1.78 19.47846154 10.94295592 0.052510364 NAGK 6.618333333 57.91769231 8.751099316 0.05266822 LGMN 11.48833333 50.06846154 4.358200627 0.052749415 GCDH 2.618333333 29.30769231 11.1932625 0.052854704 CPNE1 8.236666667 41.49307692 5.037605454 0.052940324 VMA21 2.865 13.77230769 4.8070882 0.052973039 D830031N03RIK 0.346666667 6.445384615 18.59245562 0.05308216 UCK2 4.32 27.92846154 6.464921652 0.053105139 SRP68 9.048333333 70.17 7.755019341 0.053137657 SLC25A30 0 21.66076923 #DIV/0! 0.053274355 ZFP558 0.768333333 20.02846154 26.06741198 0.053322948 PHTF1 0.896666667 31.32846154 34.93880469 0.05347776 HERC6 1.573333333 10.14153846 6.44589309 0.053846185 RCOR1 6.696666667 63.35615385 9.460849255 0.053868948 FBXL4 1.75 32.24461538 18.42549451 0.053889135 FBXL19 1.071666667 12.73076923 11.87941141 0.054084426 KDM6A 5.525 17.71076923 3.205569092 0.054545687 RAPH1 2.233333333 39.28076923 17.58840413 0.054784469 TANC2 0.118333333 10.27923077 86.86673889 0.05487343 ABCE1 55.66166667 200.5246154 3.602562183 0.054974313 RMND1 0.41 29.31615385 71.50281426 0.055302636 C1QTNF6 0 1.048461538 #DIV/0! 0.055399921 MAF1 17.76666667 100.4276923 5.652590561 0.055451124 ZFP869 6.383333333 55.8 8.74151436 0.055502064 FAM125B 0.116666667 3.541538462 30.35604396 0.055627209 RNF40 10.07833333 31.58076923 3.133530931 0.055641091 ZSCAN12 0.526666667 9.412307692 17.8714703 0.055665583 FAM49B 2.506666667 10.73923077 4.284267594 0.05577894 SUCLA2 73.88833333 148.5692308 2.010726512 0.055789996 CCDC126 0 20.03538462 #DIV/0! 0.055798969 SLC25A12 0.403333333 25.63384615 63.55499046 0.055851423 ERCC2 0.231666667 3.83 16.5323741 0.055878132 UBOX5 6.57 36.27461538 5.521250439 0.055904215 NOS3 0.686666667 12.66846154 18.44921583 0.055905624 CERCAM 0.83 3.07 3.698795181 0.055944772 NCOA7 3.856666667 56.52846154 14.65733661 0.055945052 BCL2 2.008333333 16.59230769 8.261729971 0.056008723 MAGEB18 0.2 1.033846154 5.169230769 0.05608565 GTPBP5 0.228333333 25.01846154 109.5699045 0.056248586 CPEB4 0.836666667 24.53692308 29.32699969 0.056407253 HAX1 30.27666667 126.9284615 4.19228652 0.056534504 GLCCI1 0.158333333 11.92076923 75.28906883 0.056835057 CCL24 0.786666667 2.102307692 2.672425033 0.056862408 ZFP808 12.35166667 132.1638462 10.700082 0.057000052 ADIPOR2 5.226666667 37.31615385 7.139570251 0.057117537 RAB35 0.408333333 26.87692308 65.82103611 0.05715073 DLL4 12.24833333 35 2.857531637 0.057278061 E130311K13RIK 3.908333333 14.12538462 3.614170904 0.057379198 APOBEC3 2.563333333 42.88615385 16.73061919 0.057549875 SLC25A24 18.32166667 54.09307692 2.952410275 0.057583665 2610101N10RIK 37.03666667 78.11538462 2.109136476 0.057642267 ZMYM5 5.008333333 24.55153846 4.902137463 0.057664765 CCDC43 43.24833333 111.7946154 2.584946211 0.057668463 VKORC1L1 0.063333333 8.742307692 138.0364372 0.057806041 IL13RA1 0.016666667 7.85 471 0.05788107 MSX1 0.05 8.469230769 169.3846154 0.057982811 HMCN1 2.816666667 8.090769231 2.872462449 0.057997308 TAF6L 0.068333333 5.810769231 85.03564728 0.058254094 STAT3 8.168333333 33.56615385 4.109302654 0.058254632 ETF1 27.52 79.39615385 2.88503466 0.058342227 MFSD5 7.451666667 41.13769231 5.520602859 0.05866687 YY2 0.06 6.092307692 101.5384615 0.058761486 SLC7A1 6.753333333 20.11769231 2.978927785 0.058828552 RNF185 7.015 80.98538462 11.54460223 0.05890966 CYP26B1 3.913333333 26.37230769 6.739090552 0.058910796 DDX3Y 7.835 46.02769231 5.874625693 0.05895258 IMP4 42.61166667 106.0707692 2.489242443 0.059341979 SERTAD1 7.193333333 52.86538462 7.349219363 0.059362584 PGCP 2.616666667 41.60230769 15.89897109 0.059751388 PFKP 6.793333333 30.24538462 4.452215596 0.059823579 IPMK 1.013333333 8.623076923 8.509615385 0.059838428 VEGFA 0.476666667 2.713076923 5.691769769 0.059863499 E2F2 0.098333333 11.65615385 118.5371578 0.060057838 ARRDC1 5.116666667 40.29538462 7.875319469 0.060236708 PLEKHG5 1.643333333 9.620769231 5.854423467 0.060363717 PHF13 0.523333333 19.32230769 36.92160706 0.060421909 COQ4 19.20166667 68.86692308 3.586507581 0.06045569 ALDH4A1 0.32 3.928461538 12.27644231 0.060509956 4933403F05RIK 9.585 27.94307692 2.915292324 0.06051212 PAPD4 3.011666667 62.82461538 20.86041463 0.060657403 ZFP647 0.058333333 33.44923077 573.4153846 0.06068685 LSM4 15.04 58.13923077 3.865640344 0.060767276 CAPG 2.843333333 72.77769231 25.59590585 0.060879157 RNF2 44.29333333 98.41384615 2.221865882 0.060931071 LIN54 0.211666667 16.89307692 79.80981224 0.060934324 CDC37L1 0.216666667 16.32538462 75.34792899 0.061058673 2610002M06RIK 0.818333333 6.697692308 8.184552718 0.061092923 ARMCX3 8.833333333 36.69461538 4.154107402 0.061330159 TTC37 5.881666667 29.13384615 4.953331735 0.061347448 PARP6 1.473333333 23.45230769 15.9178559 0.061450809 RBM7 70.67 157.5892308 2.229931099 0.061570105 ADAT2 0 28.44230769 #DIV/0! 0.061838009 PTPMT1 0 14.89461538 #DIV/0! 0.061985931 RTEL1 0.345 25.66 74.37681159 0.06221779 DCP1B 0.226666667 2.858461538 12.61085973 0.062376621 CRIM1 0.54 6.808461538 12.60826211 0.062729098 STK35 1.875 36.02230769 19.21189744 0.062962924 IL4RA 0.056666667 6.492307692 114.5701357 0.062976524 CCNT2 13.215 43.71923077 3.308303501 0.063205018 BAG2 20.57833333 94.91230769 4.612244644 0.063265705 SORBS2 0.226666667 9.810769231 43.28280543 0.063290001 PHF10 3.685 32.13153846 8.719549108 0.06337384 MOGAT2 0.05 52.81 1056.2 0.063468062 ARIH2 2.333333333 18.13153846 7.770659341 0.063470474 PACSIN2 13.56 64.47 4.754424779 0.063478507 YIPF1 3.13 37.29615385 11.9157041 0.063554766 COG6 3.126666667 38.22307692 12.22486469 0.063747439 SLC7A6 4.208333333 15.10076923 3.588301599 0.063782233 2310001A20RIK 2.845 55.87230769 19.63877248 0.064090499 D630042P16RIK 0 12.96307692 #DIV/0! 0.064146809 STK4 3.62 15.75769231 4.352953676 0.064174954 FXC1 35.825 94.07769231 2.626034677 0.064185248 ZFP369 2.483333333 10.37846154 4.179246257 0.064303184 KIF3B 0.043333333 4.393076923 101.3786982 0.06441931 SEC24D 5.013333333 32.95538462 6.573547463 0.06486327 CEP135 0.323333333 13.27769231 41.06502776 0.064872529 PCGF1 0 22.00692308 #DIV/0! 0.064899955 ARL13B 2.111666667 12.52076923 5.929330338 0.064987893 ZFP810 0.08 21.91153846 273.8942308 0.065100666 ESYT1 0 30.88384615 #DIV/0! 0.06518411 CCZ1 17.35666667 80.20538462 4.621013133 0.065245485 PLEKHJ1 10.81333333 37.43153846 3.461609599 0.065324885 NOL12 16.005 57.33538462 3.582342057 0.065352199 NEURL2 0 3.716153846 #DIV/0! 0.065511114 SLC35B2 11.93833333 56.23384615 4.710359862 0.065662923 STX3 0.106666667 15.75076923 147.6634615 0.065770952 ZFP524 1.28 27.75846154 21.68629808 0.065812321 CAPN7 8.455 55.77076923 6.596187963 0.065933189 REXO4 18.115 65.04538462 3.590691947 0.066064674 TMPPE 1.016666667 7.921538462 7.791677175 0.06625231 PGGT1B 10.61 47.86692308 4.511491336 0.066290551 CMKLR1 0.501666667 4.066923077 8.106823409 0.066320641 LEPR 10.915 25.52769231 2.338771627 0.066591229 MLL5 16.92333333 38.43615385 2.271192861 0.066632225 CPE 24.92833333 147.0984615 5.900854244 0.066656079 3110002H16RIK 10.475 55.47307692 5.295759133 0.066660336 FAM18B 35.45166667 106.0323077 2.990897683 0.066824071 MYLK 6.318333333 16.80461538 2.659659517 0.066907628 NPR2 0 12.93615385 #DIV/0! 0.067048221 MAPRE2 29.54 75.37307692 2.551559815 0.067252831 POLR3H 1.106666667 10.86384615 9.816728452 0.067397529 ZDHHC7 0.008333333 9.286923077 1114.430769 0.067424431 FAT1 2.761666667 11.12384615 4.027946706 0.067442384 D19ERTD386E 0.603333333 23.59461538 39.10709732 0.067464044 EBPL 1.13 11.62076923 10.28386658 0.067566323 ILKAP 0.436666667 33.9 77.63358779 0.067683201 PIK3C2B 6.925 21.25076923 3.068703138 0.067776036 NINJ1 16.98 91.41923077 5.383935852 0.067889903 APLP1 0.921666667 23.67692308 25.68924746 0.06789714 KBTBD7 0.371666667 9.033846154 24.30631252 0.067953384 MTPAP 13.205 43.51153846 3.295080535 0.067985483 CCDC111 0.971666667 18.11384615 18.64203721 0.068052146 AIFM1 12.335 93.59307692 7.587602507 0.068283362 CGRRF1 6.303333333 72.53692308 11.50770858 0.068447187 PLAU 39.32 123.4115385 3.138645434 0.068622405 TEX261 6.128333333 40.55307692 6.617309261 0.068722977 NNT 17.38833333 50.90615385 2.927603979 0.068756325 CTXN1 1.228333333 20.71230769 16.86212295 0.069009229 NGRN 0.335 36.52538462 109.0309989 0.069080224 AACS 3.008333333 41.58153846 13.82211805 0.069255291 NAMPT 2.465 27.80076923 11.27820253 0.069272222 KLHL5 4.145 31.6 7.623642943 0.069427954 FBXL17 4.44 9.891538462 2.227823978 0.06957291 SLC25A39 29.67333333 120.4469231 4.059096487 0.06964896 GGH 6.396666667 31.18846154 4.875736562 0.069772486 ZADH2 0.131666667 5.839230769 44.34858812 0.069834529 IGFBP3 37.60833333 113.7 3.02326612 0.069870412 PABPC1L 0.125 2.477692308 19.82153846 0.07007761 TMEM175 0.411666667 27.98923077 67.99003426 0.070133209 SSFA2 6.608333333 50.53307692 7.646871666 0.070436849 GM7616 4.268333333 11.64153846 2.727420178 0.0704728 DNAJC25 0 10.49923077 #DIV/0! 0.070482756 AATF 2.943333333 42.88615385 14.5706072 0.070515129 IKBKG 5.018333333 23.21230769 4.625501367 0.070677919 BEND4 0.03 10.33769231 344.5897436 0.070719978 WDFY2 0 3.26 #DIV/0! 0.070900974 SH3PXD2B 6.605 24.56615385 3.71932685 0.07098515 MPDU1 0.543333333 13.54923077 24.93723454 0.07119844 4933439F18RIK 27.53 61.72846154 2.242225265 0.071330049 ROCK2 22.725 55.42692308 2.439028518 0.071419743 PYGO2 2.42 51.32769231 21.20979021 0.071514864 PRMT3 4.151666667 30.64461538 7.381280301 0.071527724 PDCL3 62.66333333 138.4676923 2.209708372 0.071574233 ZFP229 0.11 2.258461538 20.53146853 0.071632948 ANKMY2 8.108333333 51.18769231 6.312973358 0.071726681 PIGH 5.813333333 37.59846154 6.467625265 0.07174143 SMAD2 16.53 63.96615385 3.869700777 0.071751137 RAD17 3.868333333 22.01153846 5.690186591 0.071818302 RPS19BP1 14.89 41.31307692 2.774551842 0.071825088 TSNAX 8.946666667 47.33692308 5.291012266 0.071872299 MRPL2 51.55833333 123.6776923 2.398791511 0.071975114 FAM101B 5.973333333 20.17230769 3.37706044 0.072065154 DCAF4 0.515 21.47 41.68932039 0.072109056 AU041133 1.098333333 22.56 20.54021244 0.072256734 UTP3 40.45833333 92.13538462 2.27729066 0.072281619 GHITM 104.5366667 229.7469231 2.197764004 0.072408307 PWP1 11.47166667 53.19153846 4.636775109 0.072681631 NGLY1 1.963333333 27.76230769 14.14039441 0.072980173 LCMT1 7.988333333 48.44615385 6.064613459 0.073087799 GUSB 2.208333333 54.70923077 24.77399129 0.073104179 ERLINI 0.821666667 28.54384615 34.73896084 0.073439545 PEX1 1.008333333 13.02615385 12.91849968 0.073596884 ZFP213 0 2.616153846 #DIV/0! 0.07364258 1810043G02RIK 3.758333333 42.48230769 11.3034965 0.073815133 PPM1M 9.055 55.05230769 6.079768933 0.074119249 FAF1 0.28 21.60384615 77.15659341 0.074282706 MPG 6.378333333 41.29230769 6.473839722 0.074284242 FEM1B 15.08166667 47.09230769 3.122486973 0.074313525 PRND 91.23333333 413.7092308 4.534628032 0.074340949 LGALS9 0 17.82230769 #DIV/0! 0.074396424 AFF4 5.818333333 21.55538462 3.704735253 0.074543688 SYT11 1.373333333 13.87846154 10.10567588 0.074599147 THAP7 1.876666667 28.75846154 15.32422462 0.074762579 FANCA 0.75 4.398461538 5.864615385 0.074842805 BRCA1 0.605 7.436923077 12.29243484 0.075035847 ZFP395 1.325 4.239230769 3.199419448 0.075184804 FASTKD2 2.106666667 34.70846154 16.47553554 0.075317103 AA960436 2.48 27.60076923 11.12934243 0.075450343 SCN2B 0.65 11.79076923 18.13964497 0.075488674 OIT3 2.066666667 50.04615385 24.21588089 0.075564105 FTSJ1 5.628333333 23.77 4.223275096 0.075633763 PRSS43 0.656666667 1.351538462 2.058180398 0.075737719 2310011J03RIK 0.973333333 12.27538462 12.61169652 0.075772075 MTERFD3 1.116666667 33.04538462 29.59288175 0.075936529 GCOM1 30.17166667 109.2938462 3.622400027 0.076142485 RHPN2 1.756666667 9.225384615 5.251642096 0.076437756 ERO1L 3.411666667 17.92461538 5.253917553 0.076475266 GLT25D1 2.668333333 28.42692308 10.65343776 0.07649072 HOXB5 0 4.008461538 #DIV/0! 0.076514631 ARHGAP6 0 4.700769231 #DIV/0! 0.076631422 2810408M09RIK 9.125 33.52076923 3.673508957 0.076681426 HHEX 3.306666667 37.29923077 11.28000931 0.076709174 NENF 0.396666667 7.282307692 18.35875889 0.076957706 CDAN1 1.221666667 7.300769231 5.97607304 0.077035418 GTPBP10 10.83166667 45.17153846 4.170322061 0.077134342 AKAP2 24.88833333 65.69692308 2.639667438 0.077150809 RFX1 0.378333333 9.636923077 25.47204338 0.077222052 CCT6B 0.416666667 2.223076923 5.335384615 0.07739899 MIB1 11.11333333 29.37076923 2.642840663 0.077413192 SFXN3 11.115 44.09615385 3.967265303 0.077614758 TPST1 0.446666667 7.065384615 15.81802526 0.077673955 TOMM22 99.79666667 229.6223077 2.300901577 0.077751857 GNG3 0.215 4.396923077 20.45080501 0.077757389 TTYH3 1.92 6.545384615 3.409054487 0.077901363 PXDN 30.36833333 69.64461538 2.293330181 0.078076924 TRMT5 0 24.12384615 #DIV/0! 0.078096776 PCDH1 0.78 25.93615385 33.25147929 0.078241262 TRF 4.176666667 38.07692308 9.116581742 0.078244798 PAPD7 0.121666667 10.72615385 88.1601686 0.078349373 FAM63A 5.275 47.83307692 9.067881881 0.078493926 DTX3 1.013333333 14.84461538 14.6492915 0.078495557 EGLN1 18.66 58.30538462 3.124618682 0.078604265 LAMB2 0.046666667 14.58538462 312.543956 0.078722122 JKAMP 25.19666667 84.03230769 3.33505653 0.078884402 UBE2G2 16.19333333 66.61384615 4.113658676 0.07927351 CD9 78.29166667 187.4415385 2.394144185 0.079393771 PAPD5 7.001666667 29.12538462 4.159778807 0.07947003 5830433M19RIK 2.936666667 14.77153846 5.030035798 0.079529283 CCDC115 4.416666667 31.77538462 7.194426705 0.079533801 SERINC3 20.18333333 58.57384615 2.902089818 0.079937391 TBC1D4 0.49 18.47538462 37.70486656 0.07997626 ZFP936 0.355 1.615384615 4.550379198 0.080109918 FAM158A 0 15.91230769 #DIV/0! 0.080445323 ETAA1 0.543333333 10.66692308 19.63237376 0.080705637 MYST1 0 35.48153846 #DIV/0! 0.080787758 MICAL2 1.843333333 7.543846154 4.092502434 0.081485709 1700021F05RIK 45.13166667 130.0023077 2.880512006 0.081639691 AFTPH 0 10.92769231 #DIV/0! 0.081703171 BLM 9.335 26.98846154 2.89110461 0.081733816 VPS13C 0.305 3.502307692 11.48297604 0.081746041 FBXW2 6.831666667 37.81461538 5.535196202 0.081782896 EHD4 11.12666667 42.60692308 3.82926211 0.081782985 ZFP746 5.821666667 28.69461538 4.928934793 0.081868957 TPP2 40.015 107.2569231 2.68041792 0.082386499 3110040N11RIK 11.76333333 45.52846154 3.870370774 0.082478516 LRRK2 0.031666667 5.944615385 187.7246964 0.082509549 MTMR11 0 18.52615385 #DIV/0! 0.082659818 POLR2H 75.4 178.6461538 2.369312385 0.08301763 GRAP 41.45833333 100.7638462 2.430484731 0.083047879 DHX32 0.07 1.777692308 25.3956044 0.083171504 EXOG 2.391666667 32.61153846 13.63548646 0.083234252 FREM1 0 2.106153846 #DIV/0! 0.083400371 ABCA3 0.055 11.17384615 203.1608392 0.083492441 ZFP692 0.093333333 27.01230769 289.4175824 0.083511612 MTRF1L 0.38 11.79461538 31.03846154 0.083565319 TTC17 0.908333333 24.64538462 27.13253352 0.083591981 NDRG4 0.048333333 22.71538462 469.9734748 0.083742907 TPRGL 6.11 54.65769231 8.945612489 0.083826264 ATP9B 4.38 30.31538462 6.921320688 0.083929184 SDC3 0.91 10.60923077 11.65849535 0.084461087 JAGN1 19.50833333 74.27230769 3.807209279 0.084512063 HOXA3 2.305 14.26692308 6.18955448 0.084568934 ANKRD49 15.33666667 72.39538462 4.720411951 0.084669253 KDM5C 7.55 16.58153846 2.19623026 0.084685266 HIST1H2BK 0 10.31923077 #DIV/0! 0.084808162 HIST3H2A 0 3.484615385 #DIV/0! 0.084868951 TATDN2 0.095 4.943846154 52.04048583 0.08494456 NRBP1 67.615 177.4661538 2.624656568 0.084947479 EPB4.1L5 3.13 17.17307692 5.486606046 0.084988786 MTMR4 1.741666667 14.32153846 8.222892897 0.085019684 GCNT1 0.055 18.89153846 343.4825175 0.085118852 MOAP1 2.406666667 20.36692308 8.46271042 0.085146926 POLM 0.046666667 12.84076923 275.1593407 0.085249177 QSOX1 0.216666667 2.013846154 9.294674556 0.085259606 SLC17A5 9.885 35.82692308 3.624372593 0.085349793 PRKCE 1.345 8.452307692 6.284243637 0.085444387 CDK5RAP3 0.12 24.28461538 202.3717949 0.08607689 ZNHIT2-PS 0 7.737692308 #DIV/0! 0.08617829 FBXW11 27.075 71.24538462 2.631408481 0.086198362 TBC1D22B 1.285 5.722307692 4.453157737 0.086479697 RSBN1L 3.188333333 19.6 6.147412441 0.086603607 FAM168B 15.53333333 44.54153846 2.867481017 0.086632754 4930452B06RIK 0 2.956923077 #DIV/0! 0.08673539 RAB23 0.118333333 13.69692308 115.7486457 0.087126177 SEMA3A 0.26 11.02769231 42.41420118 0.087255104 PIBF1 4.38 35.08538462 8.010361784 0.08735497 UBE3A 27.88166667 60.75384615 2.178989043 0.08746605 WWOX 0 13.01923077 #DIV/0! 0.087513341 LIME1 3.16 22.71307692 7.187682571 0.087514088 2210021J22RIK 1.381666667 43.14153846 31.22427392 0.087561778 STXBP5 0.216666667 5.331538462 24.60710059 0.087791523 TMC7 0.151666667 14.85153846 97.92223161 0.088096566 GM2058 9.375 65.04538462 6.938174359 0.088319952 IFFO2 3.718333333 16.18846154 4.35368755 0.088509133 MRPL38 7.89 47.35230769 6.00155991 0.088573901 CDK2AP1 41.42333333 126.6184615 3.056694171 0.088830232 FILIP1 0.146666667 5.945384615 40.53671329 0.088900629 RABAC1 35.475 106.05 2.989429175 0.089018546 SMTNL2 6.01 19.89076923 3.309612185 0.089067395 CORO1B 66.88666667 158.0946154 2.363619287 0.089086084 RNPEPL1 5.7 31.52076923 5.529959514 0.089197406 CNTROB 0.043333333 5.869230769 135.443787 0.089204152 MAPK3 68.19166667 140.4184615 2.059173333 0.089290852 TRIM13 0 16.12769231 #DIV/0! 0.089447268 MFN1 0.593333333 14.25923077 24.03241141 0.089526593 ATXN1 0.158333333 6.222307692 39.29878543 0.089556559 TOR1AIP1 6.466666667 27.20846154 4.207494052 0.08972818 4930444A02RIK 1.983333333 5.843076923 2.946089205 0.089899132 6430527G18RIK 1.82 5.698461538 3.131022823 0.089965414 PTER 3.01 20.27769231 6.736774853 0.090184994 FBXO42 0.531666667 10.18769231 19.16180371 0.090275926 ELK4 4.016666667 24.07 5.99253112 0.090321702 DHX40 4.04 24.59076923 6.086824067 0.090549444 ATP9A 0.948333333 27.15230769 28.63160741 0.090560867 PXMP3 16.93666667 61.61846154 3.638169349 0.090575993 GM5918 0.256666667 18.81384615 73.3006993 0.09066458 SEL1L 9.126666667 35.30923077 3.868798112 0.090703125 COG1 3.73 34.38230769 9.217776861 0.091096262 UTP20 2.581666667 7.744615385 2.999851021 0.091162217 METTL13 0 1.809230769 #DIV/0! 0.091314321 DTNBP1 6.423333333 31.12307692 4.845315556 0.09137728 DCBLD1 3.488333333 37.20307692 10.66500055 0.091420667 TRIP11 8.813333333 23.98076923 2.720964739 0.091457917 EDN1 2.101666667 27.69923077 13.17964985 0.09145804 TTPA 0.061666667 7.979230769 129.3929314 0.091463134 GPR180 1.023333333 10.13307692 9.902029567 0.091478453 FBXO11 23.225 57.61615385 2.480781651 0.091670491 TRP53INP1 0 19.60076923 #DIV/0! 0.091851979 TMEM147 60.07666667 168.2623077 2.800793004 0.091857268 FGFR2 0.073333333 15.16846154 206.8426573 0.091862636 SMC5 15.54666667 35.28769231 2.269791529 0.091894325 SALL4 0 59.29384615 #DIV/0! 0.091924063 ETV3 0.871666667 20.86461538 23.93646124 0.09194535 FNIP2 2.345 15.99846154 6.822371658 0.092117245 HSPA13 30.865 76.65692308 2.483619734 0.092160083 PLXNA2 1.018333333 6.062307692 5.95316631 0.092203574 TMEM115 2.766666667 19.09 6.9 0.09221924 SOLH 1.17 5.256923077 4.493096647 0.092247217 GSTZ1 2.51 64.62538462 25.74716519 0.092258383 MFSD6 0.423333333 2.280769231 5.387643852 0.092479056 2310022A10RIK 0.406666667 6.086153846 14.96595208 0.092553602 TMEM66 5.94 65.58615385 11.04144004 0.092857173 GCAT 9.278333333 42.12230769 4.539857125 0.093123416 CXCR7 11.72 53.78461538 4.589131006 0.09314384 TATDN1 3.045 24.37923077 8.006315524 0.09316526 BIN1 5.986666667 29.13615385 4.866840843 0.093255424 E2F3 0.36 5.876153846 16.32264957 0.093659226 PPP2R5A 1.905 22.96230769 12.05370483 0.093767868 DAG1 8.025 29.70769231 3.701893122 0.093858638 EZH1 0.881666667 9.670769231 10.96873637 0.093877551 REEP1 0.11 21.07153846 191.5594406 0.093879695 PHPT1 169.3266667 346.5476923 2.046622066 0.093969581 AMBRA1 1.726666667 10.70615385 6.2004752 0.094060067 SBF2 10.61666667 33.22769231 3.129766936 0.094061511 PDDC1 23.91333333 98.18 4.105659325 0.094109405 ZBTB39 0.445 7.649230769 17.18928263 0.094264899 ALG11 0.296666667 10.02307692 33.78565255 0.094288288 SGIP1 0.291666667 3.756153846 12.87824176 0.094575454 SIGIRR 0 10.66230769 #DIV/0! 0.094598079 EMP3 4.958333333 54.22846154 10.93683258 0.094824097 DGKH 0.081666667 6.36 77.87755102 0.094868476 CTNNBIP1 0.03 7.819230769 260.6410256 0.095187154 RNF141 0.951666667 42.28615385 44.43378688 0.095319 SDC2 5.173333333 51.55692308 9.965900079 0.095348192 CDYL 2.603333333 28.02076923 10.76341968 0.095410278 MTMR3 1.261666667 22.02461538 17.45676252 0.095537086 2310003H01RIK 0.46 45.96615385 99.9264214 0.09571754 MREG 0.04 3.934615385 98.36538462 0.095767806 DOT1L 4.913333333 12.80461538 2.606095397 0.095898107 PLEKHA1 20.235 77.14384615 3.812396647 0.096096971 VPS8 0.211666667 5.752307692 27.17625681 0.09615618 H2AFJ 3.13 8.043846154 2.569918899 0.09616433 GTF3C3 1.79 10.75769231 6.009883971 0.096236639 FZD7 0.318333333 1.48 4.64921466 0.096282298 HAUS2 16.255 55.17692308 3.39445851 0.096282605 LRRC42 14.73 56.98 3.868295995 0.096307002 PUS7L 0 19.13615385 #DIV/0! 0.096501578 DDX49 7.923333333 58.56307692 7.391217113 0.096688134 ARRB2 0.415 2.435384615 5.868396664 0.096710155 CUTC 0.468333333 47.42076923 101.2543115 0.096772584 RRAGA 0.716666667 28.74 40.10232558 0.096773662 HAS2 0 7.902307692 #DIV/0! 0.097054884 CUX1 3.91 31.22923077 7.987015542 0.09705562 ACOT8 0 9.064615385 #DIV/0! 0.097142277 ZFP58 0.86 19.77076923 22.98926655 0.097225082 EFNA1 152.66 317.8 2.081750295 0.097431704 PACS2 4.711666667 16.33846154 3.467660744 0.097437511 5730403B10RIK 19.50666667 57.61307692 2.953507019 0.097515148 RND3 22.19166667 111.0853846 5.00572518 0.097576798 CCDC28A 0 2.475384615 #DIV/0! 0.097626798 1500009L16RIK 2.046666667 18.86615385 9.217990479 0.097677532 SOX18 26.20333333 69.22769231 2.641942207 0.097679365 1700025G04RIK 2.005 5.525384615 2.755802801 0.097747959 KLF4 9.098333333 38.94846154 4.280834754 0.097779938 PDLIM1 4.161666667 54.08384615 12.99571794 0.097813795 RELN 0 2.663846154 #DIV/0! 0.098090859 LETMD1 0.741666667 42.64461538 57.49835782 0.098178385 PYCR2 13.975 51.68 3.6980322 0.098386231 BCAS3 0.095 10.15615385 106.9068826 0.098499825 CHN1 6.918333333 28.86538462 4.172303245 0.09863188 LDLR 1.35 5.981538462 4.430769231 0.098711275 PKD2L2 0.35 2.766153846 7.903296703 0.098945217 MTAP4 25.88333333 60.14076923 2.323532617 0.098988923 ROBO2 0 4.482307692 #DIV/0! 0.099108054 COPZ2 0.541666667 22.39692308 41.34816568 0.09915995 INTS7 36.29333333 85.40307692 2.353134008 0.099393182 AGPAT4 17.75 47.84769231 2.695644637 0.099419301 CFL2 44.70166667 105.5246154 2.360641633 0.099522782 CD2AP 39.62166667 93.75153846 2.366168472 0.099591675 ZBTB10 3.166666667 28.44923077 8.983967611 0.099729084 1810008A18RIK 0.483333333 21.95 45.4137931 0.099791657 TRIOBP 2.751666667 29.92 10.87341005 0.099835126 9030025P20RIK 7.903333333 17.32538462 2.192161697 0.099870069 CRY2 2.626666667 14.22153846 5.414291292 0.099894165 DDX26B 9.481666667 25.61538462 2.701569831 0.099983822 

We claim: 1-12. (canceled)
 13. A substantially pure, isolated population of arterial endothelial cells obtained by culturing mesodermal cells in a serum-free, albumin-free, chemically defined culture medium that is substantially free of insulin and comprises a fibroblast growth factor (FGF), a vascular endothelial growth factor (VEGF), a Notch agonist, a TGF-beta inhibitor, and an inhibitor of inositol monophosphatase, whereby a cell population comprising arterial endothelial cells is obtained; wherein the arterial endothelial cells of the population express one or more markers selected from the group consisting of Ephrin B2 (EFNB2), neuropilin1 (NRP-1), Delta-like 4 (DLL4), CD44, CXCR4/CD184, Gap Junction Protein Alpha-4 (GJA4), Hey1, Jagged-1 (JAG1), Notch1, and Notch4.
 14. The isolated population of claim 13 comprising at least 90% arterial endothelial cells.
 15. The isolated population of claim 13 comprising at least 99% arterial endothelial cells.
 16. A substantially pure, isolated population of pluripotent stem cell-derived arterial endothelial cells obtained by culturing human pluripotent stem cells for a period of about two days in a serum-free, albumin-free, chemically defined cell culture medium comprising a Bone Morphogenetic Protein (BMP), Activin A, and an activator of Wnt/β-catenin signaling to obtain a cell population comprising mesodermal cells.
 17. The isolated population of claim 16 comprising at least 90% arterial endothelial cells.
 18. The isolated population of claim 16 comprising at least 99% arterial endothelial cells. 19-23. (canceled)
 24. A method of in vitro screening of an agent, comprising (a) contacting a test agent to the population of arterial endothelial cells of claim 13; and (b) detecting an effect of the agent on adhesion of leukocytes to the contacted arterial endothelial cells.
 25. The method of claim 24, wherein detecting comprises performing a method selected from the group consisting of a leukocyte adhesion assay, RNA sequencing, gene expression profiling, transcriptome analysis, metabolome analysis, detecting reporter or sensor, protein expression profiling, Forster resonance energy transfer (FRET), metabolic profiling, and microdialysis. 26-27. (canceled)
 28. A kit for obtaining arterial endothelial cells, the kit comprising: (i) a serum-free, albumin-free, chemically defined culture medium suitable for differentiation of mesodermal cells into arterial endothelial cells, wherein the culture medium is substantially free of insulin and comprises a fibroblast growth factor (FGF), a vascular endothelial growth factor (VEGF), and at least one of a Notch agonist, a TGF-beta inhibitor, and an inhibitor of inositol monophosphatase; and (ii) instructions describing a method for differentiating mesodermal cells into arterial endothelial cells, the method employing the culture medium.
 29. The kit of claim 28, further comprising: (a) a serum-free, albumin-free, chemically defined culture medium suitable for differentiation of human pluripotent stem cells into mesodermal cells, wherein the culture medium comprises a BMP, Activin A, and an activator of Wnt/β-catenin signaling; and (b) instructions describing a method for differentiating human pluripotent stem cells into arterial endothelial cells, the method employing the culture medium of (a).
 30. The isolated population of claim 13, wherein the mesodermal cells express one or more mesodermal markers selected from the group consisting of Brachyury (T), EMOS, FOXA2, MIXL1, MSX1, and MSX2.
 31. The arterial endothelial cells of claim 13, wherein the cells are cultured for about 6 days until a cell population comprising at least 80% human Ephrin B2 (EFNB2)-positive arterial endothelial and comprising fewer than 20% EphB4⁺ cells is obtained.
 32. The isolated population of claim 16, wherein the mesodermal cells express one or more mesodermal markers selected from the group consisting of Brachyury (T), EMOS, FOXA2, MIXL1, MSX1, and MSX2.
 33. The method of claim 16, wherein the pluripotent stem cells are human embryonic stem cells or human induced pluripotent stem cells.
 34. The method of claim 16, wherein the activator of Wnt/β-catenin signaling is a Gsk3 inhibitor.
 35. The method of claim 34, wherein the Gsk3 inhibitor is selected from the group consisting of CHIR 99021, CHIR 98014, BIO-acetoxime, BIO, LiCl, SB 216763, SB 415286, AR A014418, 1-Azakenpaullone, and Bis-7-indolylmaleimide.
 36. The method of claim 16, wherein the Notch agonist is selected from the group consisting of Resveratrol (3,4′,5-trihydroxystilbene), valproic acid, and suberoyl bishydroxamic acid.
 37. The method of claim 16, wherein the TGF-beta inhibitor is SB431542.
 38. The method of claim 16, wherein the inhibitor of inositol monophosphatase is L-690,330. 